From 3c2b90b654842499a30e3a001000c61b70d6271d Mon Sep 17 00:00:00 2001
From: jamsonchan <jamsonchan@potix.com>
Date: Tue, 2 Jan 2024 21:16:10 +0800
Subject: [PATCH] ZK-3853: Tree supports 3-states selection(WIP)

---
 zkdoc/release-note                            |   3 +
 .../zktest/test2/F100_ZK_3853Composer.java    | 149 ++++++++
 .../zktest/test2/F100_ZK_3853_2Composer.java  |  70 ++++
 .../src/main/webapp/test2/F100-ZK-3853-1.zul  | 104 ++++++
 .../src/main/webapp/test2/F100-ZK-3853-2.zul  |  28 ++
 .../src/main/webapp/test2/F100-ZK-3853-3.zul  | 125 +++++++
 zktest/src/main/webapp/test2/F100-ZK-3853.zul | 219 ++++++++++++
 .../zktest/zats/test2/F100_ZK_3853_1Test.java | 182 ++++++++++
 .../zktest/zats/test2/F100_ZK_3853_2Test.java |  46 +++
 .../zktest/zats/test2/F100_ZK_3853_3Test.java | 132 +++++++
 .../java/org/zkoss/zul/AbstractTreeModel.java | 198 ++++++++++-
 zul/src/main/java/org/zkoss/zul/Tree.java     | 322 +++++++++++++++++-
 .../org/zkoss/zul/event/TreeDataEvent.java    |  18 +-
 .../org/zkoss/zul/ext/PartialSelectable.java  |  82 +++++
 .../zul/ext/TreePartialSelectableModel.java   | 113 ++++++
 zul/src/main/resources/metainfo/xml/zul.xsd   |   1 +
 zul/src/main/resources/web/js/zul/sel/Tree.ts | 117 +++++++
 .../main/resources/web/js/zul/sel/Treecell.ts |   4 +-
 .../main/resources/web/js/zul/sel/Treecol.ts  |   6 +-
 .../main/resources/web/js/zul/sel/Treeitem.ts |  31 ++
 .../main/resources/web/js/zul/sel/Treerow.ts  |  10 +-
 .../resources/web/js/zul/sel/less/tree.less   |  19 ++
 22 files changed, 1938 insertions(+), 41 deletions(-)
 create mode 100644 zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853Composer.java
 create mode 100644 zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853_2Composer.java
 create mode 100644 zktest/src/main/webapp/test2/F100-ZK-3853-1.zul
 create mode 100644 zktest/src/main/webapp/test2/F100-ZK-3853-2.zul
 create mode 100644 zktest/src/main/webapp/test2/F100-ZK-3853-3.zul
 create mode 100644 zktest/src/main/webapp/test2/F100-ZK-3853.zul
 create mode 100644 zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_1Test.java
 create mode 100644 zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_2Test.java
 create mode 100644 zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_3Test.java
 create mode 100644 zul/src/main/java/org/zkoss/zul/ext/PartialSelectable.java
 create mode 100644 zul/src/main/java/org/zkoss/zul/ext/TreePartialSelectableModel.java

diff --git a/zkdoc/release-note b/zkdoc/release-note
index 89e47469b28..05ebf37dcd9 100644
--- a/zkdoc/release-note
+++ b/zkdoc/release-note
@@ -9,6 +9,7 @@ ZK 10.0.0
   ZK-5596: Simplify the JavaScript url when enable embedded mode
   ZK-5590: Reimplement sourcemap in ZK 10
   ZK-5512: Support for Listening to Space Key Pressed
+  ZK-3853: Tree supports 3-states selection
 
 * Bugs
   ZK-5393: Update ZK jars to jakarta-friendly uploads
@@ -38,6 +39,8 @@ ZK 10.0.0
     simplifying the source to enable embedded mode.
   + The setContent() method of Comboitem, Menu, and Navitem now only accepts a safe HTML content.
     i.e. The content will be sanitized before rendering, please don't use JavaScript content.
+  + Tree support tri-state selection, use new boolean attribute `indeterminate` to enable.
+
    --------
 ZK 10.0.0-Beta
 Oct 17, 2023
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853Composer.java b/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853Composer.java
new file mode 100644
index 00000000000..056dfc6e05c
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853Composer.java
@@ -0,0 +1,149 @@
+/* F100_ZK_3853Composer.java
+
+        Purpose:
+
+        Description:
+
+        History:
+                Fri Dec 15 17:53:26 CST 2023, Created by jamson
+
+Copyright (C) 2023 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.test2;
+
+import org.zkoss.zk.ui.select.SelectorComposer;
+import org.zkoss.zk.ui.select.annotation.Listen;
+import org.zkoss.zk.ui.select.annotation.Wire;
+import org.zkoss.zul.Button;
+import org.zkoss.zul.DefaultTreeModel;
+import org.zkoss.zul.DefaultTreeNode;
+import org.zkoss.zul.Tree;
+import org.zkoss.zul.TreeNode;
+import org.zkoss.zul.Treechildren;
+import org.zkoss.zul.Treeitem;
+import org.zkoss.zul.Window;
+
+public class F100_ZK_3853Composer extends SelectorComposer<Window> {
+
+	DefaultTreeModel model;
+	@Wire
+	Tree tree, tree2;
+	@Wire
+	Button b6, b13;
+	@Override
+	public void doAfterCompose(Window component) throws Exception {
+		super.doAfterCompose(component);
+		model = new DefaultTreeModel(
+				new DefaultTreeNode(null,
+					new DefaultTreeNode[] {
+						new DefaultTreeNode("1",
+							new DefaultTreeNode[] {
+								new DefaultTreeNode("2"),
+								new DefaultTreeNode("3")
+							}),
+						new DefaultTreeNode("4"),
+						new DefaultTreeNode("5",
+							new DefaultTreeNode[] {
+								new DefaultTreeNode("6",
+									new DefaultTreeNode[] {
+										new DefaultTreeNode("7"),
+										new DefaultTreeNode("8"),
+										new DefaultTreeNode("9",
+											new DefaultTreeNode[] {
+												new DefaultTreeNode("10"),
+												new DefaultTreeNode("11"),
+												new DefaultTreeNode("12"),
+											}
+										)
+									}
+								),
+								new DefaultTreeNode("13"),
+								new DefaultTreeNode("14")
+							}
+						)
+					}
+				)
+		);
+		tree.setModel(model);
+		tree.setIndeterminate(true);
+	}
+
+	@Listen("onClick=#b1")
+	public void b1() {
+		tree.setModel(tree.getModel() == null ? model : null);
+	}
+
+	@Listen("onClick=#b2")
+	public void b2() {
+		tree.setIndeterminate(!tree.isIndeterminate());
+	}
+
+	@Listen("onClick=#b3")
+	public void b3() {
+		model.setIndeterminate(!model.isIndeterminate());
+	}
+
+	@Listen("onClick=#b4")
+	public void b4() {
+		tree.setMultiple(!tree.isMultiple());
+	}
+
+	@Listen("onClick=#b5")
+	public void b5() {
+		model.setMultiple(!model.isMultiple());
+	}
+
+	@Listen("onClick=#b6")
+	public void b6() {
+		b6.setLabel("sel:" + String.valueOf(tree.getSelectedCount()) + " par:" + String.valueOf(tree.getPartialCount()));
+	}
+
+	@Listen("onClick=#b7")
+	public void b7() {
+		TreeNode root = (TreeNode) model.getRoot(),
+				targetParent = root.getChildAt(2).getChildAt(0).getChildAt(2),
+				newNode = new DefaultTreeNode("Model inserted");
+		targetParent.insert(newNode, 1);
+	}
+
+	@Listen("onClick=#b8")
+	public void b8() {
+		TreeNode root = (TreeNode) model.getRoot(),
+				targetParent = root.getChildAt(2).getChildAt(0).getChildAt(2);
+		targetParent.remove(1);
+	}
+
+	@Listen("onClick=#b11")
+	public void b11() {
+		tree2.setIndeterminate(!tree2.isIndeterminate());
+	}
+
+	@Listen("onClick=#b12")
+	public void b12() {
+		tree2.setMultiple(!tree2.isMultiple());
+	}
+
+	@Listen("onClick=#b13")
+	public void b13() {
+		b13.setLabel("sel:" + String.valueOf(tree2.getSelectedCount()) + " par:" + String.valueOf(tree2.getPartialCount()));
+	}
+
+	@Listen("onClick=#b14")
+	public void b14() {
+		Treechildren treechildren = tree2.getTreechildren();
+		Treeitem t1 = (Treeitem) treechildren.getFirstChild(),
+				t4 = (Treeitem) t1.getNextSibling(),
+				t5 = (Treeitem) t4.getNextSibling();
+
+		Treeitem ti = new Treeitem();
+		ti.setLabel("inserted");
+		ti.setSelected(true);
+		treechildren.insertBefore(ti, treechildren.getFirstChild());
+	}
+
+	@Listen("onClick=#b15")
+	public void b15() {
+		Treechildren treechildren = tree2.getTreechildren();
+		treechildren.removeChild(treechildren.getFirstChild());
+	}
+}
\ No newline at end of file
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853_2Composer.java b/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853_2Composer.java
new file mode 100644
index 00000000000..98237bb85f4
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/F100_ZK_3853_2Composer.java
@@ -0,0 +1,70 @@
+/* F100_ZK_3853_2Composer.java
+
+        Purpose:
+                
+        Description:
+                
+        History:
+                Tue Jan 02 18:48:59 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.test2;
+
+import org.zkoss.zk.ui.select.SelectorComposer;
+import org.zkoss.zk.ui.select.annotation.Listen;
+import org.zkoss.zk.ui.select.annotation.Wire;
+import org.zkoss.zul.DefaultTreeModel;
+import org.zkoss.zul.DefaultTreeNode;
+import org.zkoss.zul.Tree;
+import org.zkoss.zul.Window;
+
+public class F100_ZK_3853_2Composer extends SelectorComposer<Window> {
+	DefaultTreeModel model;
+	@Wire
+	Tree tree;
+	@Override
+	public void doAfterCompose(Window component) throws Exception {
+		super.doAfterCompose(component);
+		model =
+		new DefaultTreeModel(
+			new DefaultTreeNode(null,
+				new DefaultTreeNode[] {
+					new DefaultTreeNode("0",
+						new DefaultTreeNode[] {
+							new DefaultTreeNode("1"),
+							new DefaultTreeNode("2")
+						}
+					),
+					new DefaultTreeNode("3"),
+					new DefaultTreeNode("4",
+						new DefaultTreeNode[] {
+							new DefaultTreeNode("5",
+								new DefaultTreeNode[] {
+									new DefaultTreeNode("6"),
+									new DefaultTreeNode("7"),
+									new DefaultTreeNode("8",
+										new DefaultTreeNode[] {
+											new DefaultTreeNode("9"),
+											new DefaultTreeNode("10"),
+											new DefaultTreeNode("11"),
+										}
+									)
+								}
+							),
+							new DefaultTreeNode("12"),
+							new DefaultTreeNode("13")
+						}
+					)
+				}
+			)
+		);
+		tree.setModel(model);
+		tree.setIndeterminate(true);
+	}
+
+	@Listen("onClick=#btn")
+	public void toogleModel() {
+		tree.setModel(tree.getModel() == null ? model : null);
+	}
+}
diff --git a/zktest/src/main/webapp/test2/F100-ZK-3853-1.zul b/zktest/src/main/webapp/test2/F100-ZK-3853-1.zul
new file mode 100644
index 00000000000..b944634a5eb
--- /dev/null
+++ b/zktest/src/main/webapp/test2/F100-ZK-3853-1.zul
@@ -0,0 +1,104 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+F100-ZK-3853-1.zul
+
+        Purpose:
+
+        Description:
+
+        History:
+                Tue Jan 02 16:00:24 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+-->
+<zk>
+	<label multiline="true">
+		Tri-State Tree Pure Component Test.
+		click checkbox and check whether all updates are correct.
+	</label>
+	<tree indeterminate="true">
+		<treecols>
+			<treecol label="treecol" />
+		</treecols>
+		<treechildren>
+			<treeitem open="false">
+				<treerow>
+					<treecell label="0" />
+				</treerow>
+				<treechildren>
+					<treeitem>
+						<treerow>
+							<treecell label="1"/>
+						</treerow>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="2" />
+						</treerow>
+					</treeitem>
+				</treechildren>
+			</treeitem>
+			<treeitem>
+				<treerow>
+					<treecell label="3" />
+				</treerow>
+			</treeitem>
+			<treeitem open="false">
+				<treerow>
+					<treecell label="4" />
+				</treerow>
+				<treechildren>
+					<treeitem open="false">
+						<treerow>
+							<treecell label="5" />
+						</treerow>
+						<treechildren>
+							<treeitem open="false">
+								<treerow>
+									<treecell label="6" />
+								</treerow>
+							</treeitem>
+							<treeitem>
+								<treerow>
+									<treecell label="7" />
+								</treerow>
+							</treeitem>
+							<treeitem open="false">
+								<treerow>
+									<treecell label="8" />
+								</treerow>
+								<treechildren>
+									<treeitem>
+										<treerow>
+											<treecell label="9" />
+										</treerow>
+									</treeitem>
+									<treeitem>
+										<treerow>
+											<treecell label="10" />
+										</treerow>
+									</treeitem>
+									<treeitem>
+										<treerow>
+											<treecell label="11" />
+										</treerow>
+									</treeitem>
+								</treechildren>
+							</treeitem>
+						</treechildren>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="12" />
+						</treerow>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="13" />
+						</treerow>
+					</treeitem>
+				</treechildren>
+			</treeitem>
+		</treechildren>
+	</tree>
+</zk>
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/F100-ZK-3853-2.zul b/zktest/src/main/webapp/test2/F100-ZK-3853-2.zul
new file mode 100644
index 00000000000..20b6a999eb9
--- /dev/null
+++ b/zktest/src/main/webapp/test2/F100-ZK-3853-2.zul
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+F100-ZK-3853-2.zul
+
+        Purpose:
+
+        Description:
+
+        History:
+                Tue Jan 02 18:38:49 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+-->
+<zk>
+	<label multiline="true">
+		Tri-State Tree with Model Test.
+		1. click checkbox and check whether all updates are correct.
+		2. click `toggle model` button, check the model save all state correctly after un-bind and re-bind.
+	</label>
+	<window apply="org.zkoss.zktest.test2.F100_ZK_3853_2Composer">
+		<button id="btn" label="toggle model"/>
+		<tree id="tree">
+			<treecols>
+				<treecol label="treecol" />
+			</treecols>
+		</tree>
+	</window>
+</zk>
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/F100-ZK-3853-3.zul b/zktest/src/main/webapp/test2/F100-ZK-3853-3.zul
new file mode 100644
index 00000000000..5e1d19be0a7
--- /dev/null
+++ b/zktest/src/main/webapp/test2/F100-ZK-3853-3.zul
@@ -0,0 +1,125 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+F100-ZK-3853-3.zul
+
+        Purpose:
+
+        Description:
+
+        History:
+                Tue Jan 02 19:14:59 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+-->
+<zk>
+	<label multiline="true">
+		Tri-State Tree Pure Component Test.
+		click `toggle checkmark`, `toggle multiple`, `toggle indeterminate` to see these state switch according to the following rules:
+		* If toggle `indeterminate` false -> true, `checkmark` and `multiple` will be set to true at the same time.
+		* If toggle `multiple` or `checkmark` true -> false, if `indeterminate` is true, then it'll be set to false.
+		* If every mode change to `indeterminate` mode, initially it'll generate 3-state based on current checkmark.
+	</label>
+	<button label="toggle checkmark">
+		<attribute name="onClick">
+			tree.setCheckmark(!tree.isCheckmark());
+			System.out.println(tree.isCheckmark() + " " + tree.isMultiple() + " " + tree.isIndeterminate());
+		</attribute>
+	</button>
+	<button label="toggle multiple">
+		<attribute name="onClick">
+			tree.setMultiple(!tree.isMultiple());
+			System.out.println(tree.isCheckmark() + " " + tree.isMultiple() + " " + tree.isIndeterminate());
+		</attribute>
+	</button>
+	<button label="toggle indeterminate">
+		<attribute name="onClick">
+			tree.setIndeterminate(!tree.isIndeterminate());
+			System.out.println(tree.isCheckmark() + " " + tree.isMultiple() + " " + tree.isIndeterminate());
+		</attribute>
+	</button>
+	<tree id="tree">
+		<treecols>
+			<treecol label="treecol" />
+		</treecols>
+		<treechildren>
+			<treeitem>
+				<treerow>
+					<treecell label="0" />
+				</treerow>
+				<treechildren>
+					<treeitem>
+						<treerow>
+							<treecell label="1"/>
+						</treerow>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="2" />
+						</treerow>
+					</treeitem>
+				</treechildren>
+			</treeitem>
+			<treeitem>
+				<treerow>
+					<treecell label="3" />
+				</treerow>
+			</treeitem>
+			<treeitem>
+				<treerow>
+					<treecell label="4" />
+				</treerow>
+				<treechildren>
+					<treeitem>
+						<treerow>
+							<treecell label="5" />
+						</treerow>
+						<treechildren>
+							<treeitem>
+								<treerow>
+									<treecell label="6" />
+								</treerow>
+							</treeitem>
+							<treeitem>
+								<treerow>
+									<treecell label="7" />
+								</treerow>
+							</treeitem>
+							<treeitem>
+								<treerow>
+									<treecell label="8" />
+								</treerow>
+								<treechildren>
+									<treeitem>
+										<treerow>
+											<treecell label="9" />
+										</treerow>
+									</treeitem>
+									<treeitem>
+										<treerow>
+											<treecell label="10" />
+										</treerow>
+									</treeitem>
+									<treeitem>
+										<treerow>
+											<treecell label="11" />
+										</treerow>
+									</treeitem>
+								</treechildren>
+							</treeitem>
+						</treechildren>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="12" />
+						</treerow>
+					</treeitem>
+					<treeitem>
+						<treerow>
+							<treecell label="13" />
+						</treerow>
+					</treeitem>
+				</treechildren>
+			</treeitem>
+		</treechildren>
+	</tree>
+</zk>
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/F100-ZK-3853.zul b/zktest/src/main/webapp/test2/F100-ZK-3853.zul
new file mode 100644
index 00000000000..b93a3241cc5
--- /dev/null
+++ b/zktest/src/main/webapp/test2/F100-ZK-3853.zul
@@ -0,0 +1,219 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+F100-ZK-3853.zul
+
+        Purpose:
+
+        Description:
+
+        History:
+                Thu Dec 14 15:36:18 CST 2023, Created by jamson
+
+Copyright (C) 2023 Potix Corporation. All Rights Reserved.
+-->
+<zk>
+	<!--
+			cols -> col -> *		row -> cell -> *
+			/						/
+		tree ->     children    -> item
+			\						\
+			foot -> footer ->	*	children
+	-->
+	<window apply="org.zkoss.zktest.test2.F100_ZK_3853Composer">
+		<button id="b1" label="Model"/>
+		<button id="b2" label="C tri"/>
+		<button id="b3" label="M tri"/>
+		<button id="b4" label="C mul"/>
+		<button id="b5" label="M mul"/>
+		<button id="b6" label=""/>
+		<button id="b7" label="insert"/>
+		<button id="b8" label="remove"/>
+		<div>
+			<label id="lb"/>
+		</div>
+		<tree id="tree">
+			<treecols>
+				<treecol label="Name" />
+			</treecols>
+		</tree>
+
+
+		<button id="b11" label="C tri"/>
+		<button id="b12" label="C mul"/>
+		<button id="b13" label=""/>
+		<button id="b14" label="insert"/>
+		<button id="b15" label="remove"/>
+		<tree id="tree2" indeterminate="true">
+			<treecols>
+				<treecol label="Name" />
+			</treecols>
+			<treechildren>
+				<treeitem open="false">
+					<treerow>
+						<treecell label="1" />
+					</treerow>
+					<treechildren>
+						<treeitem>
+							<treerow>
+								<treecell label="2"/>
+							</treerow>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="3" />
+							</treerow>
+						</treeitem>
+					</treechildren>
+				</treeitem>
+				<treeitem>
+					<treerow>
+						<treecell label="4" />
+					</treerow>
+				</treeitem>
+				<treeitem open="false">
+					<treerow>
+						<treecell label="5" />
+					</treerow>
+					<treechildren>
+						<treeitem open="false">
+							<treerow>
+								<treecell label="6" />
+							</treerow>
+							<treechildren>
+								<treeitem open="false">
+									<treerow>
+										<treecell label="7" />
+									</treerow>
+								</treeitem>
+								<treeitem>
+									<treerow>
+										<treecell label="8" />
+									</treerow>
+								</treeitem>
+								<treeitem open="false">
+									<treerow>
+										<treecell label="9" />
+									</treerow>
+									<treechildren>
+										<treeitem>
+											<treerow>
+												<treecell label="10" />
+											</treerow>
+										</treeitem>
+										<treeitem>
+											<treerow>
+												<treecell label="11" />
+											</treerow>
+										</treeitem>
+										<treeitem>
+											<treerow>
+												<treecell label="12" />
+											</treerow>
+										</treeitem>
+									</treechildren>
+								</treeitem>
+							</treechildren>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="13" />
+							</treerow>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="14" />
+							</treerow>
+						</treeitem>
+					</treechildren>
+				</treeitem>
+			</treechildren>
+		</tree>
+
+
+		<tree mold="paging" pageSize="5" id="tree3" indeterminate="true">
+			<treecols>
+				<treecol label="Name" />
+			</treecols>
+			<treechildren>
+				<treeitem open="false">
+					<treerow>
+						<treecell label="1" />
+					</treerow>
+					<treechildren>
+						<treeitem>
+							<treerow>
+								<treecell label="2"/>
+							</treerow>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="3" />
+							</treerow>
+						</treeitem>
+					</treechildren>
+				</treeitem>
+				<treeitem>
+					<treerow>
+						<treecell label="4" />
+					</treerow>
+				</treeitem>
+				<treeitem open="false">
+					<treerow>
+						<treecell label="5" />
+					</treerow>
+					<treechildren>
+						<treeitem open="false">
+							<treerow>
+								<treecell label="6" />
+							</treerow>
+							<treechildren>
+								<treeitem open="false">
+									<treerow>
+										<treecell label="7" />
+									</treerow>
+								</treeitem>
+								<treeitem>
+									<treerow>
+										<treecell label="8" />
+									</treerow>
+								</treeitem>
+								<treeitem open="false">
+									<treerow>
+										<treecell label="9" />
+									</treerow>
+									<treechildren>
+										<treeitem>
+											<treerow>
+												<treecell label="10" />
+											</treerow>
+										</treeitem>
+										<treeitem>
+											<treerow>
+												<treecell label="11" />
+											</treerow>
+										</treeitem>
+										<treeitem>
+											<treerow>
+												<treecell label="12" />
+											</treerow>
+										</treeitem>
+									</treechildren>
+								</treeitem>
+							</treechildren>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="13" />
+							</treerow>
+						</treeitem>
+						<treeitem>
+							<treerow>
+								<treecell label="14" />
+							</treerow>
+						</treeitem>
+					</treechildren>
+				</treeitem>
+			</treechildren>
+		</tree>
+	</window>
+</zk>
\ No newline at end of file
diff --git a/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_1Test.java b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_1Test.java
new file mode 100644
index 00000000000..e0c23b06a12
--- /dev/null
+++ b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_1Test.java
@@ -0,0 +1,182 @@
+/* F100_ZK_3853_1Test.java
+
+        Purpose:
+                
+        Description:
+                
+        History:
+                Tue Jan 02 16:06:35 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.zats.test2;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import org.zkoss.test.webdriver.WebDriverTestCase;
+import org.zkoss.test.webdriver.ztl.JQuery;
+
+public class F100_ZK_3853_1Test extends WebDriverTestCase {
+
+	@Test
+	public void test() {
+		connect();
+		/*  all `open` tags are initially close */
+
+		/* Test hdcm turn to partial state */
+		clickCm(2); // check (4)
+
+		assertHdcm(2);
+		assertCm(0, 0, 1);
+		assertCm(1, 2);
+
+		/* Test hdcm turn to checked state */
+		clickCm(0, 1); // check (0, 1)
+
+		assertHdcm(1);
+		assertCm(1, 0, 1, 2);
+
+		/* Test hdcm turn to un-checked state */
+		clickCm(0, 1, 2); // un-check (0, 3, 4)
+
+		assertHdcm(0);
+		assertCm(0, 0, 1, 2);
+
+		/* Test check a close tag will update all its descendants to checked state */
+		clickopen(0, 1, 2, 3); // open (0, 4, 5, 8)
+		clickCm(4); // check (4)
+
+		assertHdcm(2);
+		for (int i = 4; i <= 13; ++i) assertCm(1, i);
+
+		/* Test un-checked a cm inside a all-selected cm will show partial state */
+		clickCm(10); // un-check (10)
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 6, 7, 9, 11, 12, 13);
+		assertCm(0, 0, 1, 2, 3, 10);
+
+		/* Test another cm shows partial state in its ancestors */
+		clickCm(1); // check (1)
+
+		assertHdcm(2);
+		assertCm(2, 0, 4, 5, 8);
+		assertCm(1, 1, 6, 7, 9, 11, 12, 13);
+		assertCm(0, 2, 3, 10);
+
+		/* Test head cm check-all and clear all partial states */
+		clickHdcm();
+
+		assertHdcm(1);
+		for (int i = 0; i <= 13; ++i) assertCm(1, i);
+
+		/* Test head cm un-check-all */
+		clickHdcm();
+
+		assertHdcm(0);
+		for (int i = 0; i <= 13; ++i) assertCm(0, i);
+
+		/* Test head cm update correctly when check cm from deep to shallow */
+		clickCm(10, 7, 3);
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 3, 7, 10);
+		assertCm(0, 0, 1, 2, 6, 9, 11, 12, 13);
+
+		clickHdcm();
+
+		assertHdcm(1);
+		for (int i = 0; i <= 13; ++i) assertCm(1, i);
+
+		clickHdcm();
+
+		assertHdcm(0);
+		for (int i = 0; i <= 13; ++i) assertCm(0, i);
+
+		/* Test head cm update correctly when check cm from shallow to deep */
+		clickCm(3, 7, 10);
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 3, 7, 10);
+		assertCm(0, 0, 1, 2, 6, 9, 11, 12, 13);
+
+		clickHdcm();
+
+		assertHdcm(1);
+		for (int i = 0; i <= 13; ++i) assertCm(1, i);
+
+		clickHdcm();
+
+		assertHdcm(0);
+		for (int i = 0; i <= 13; ++i) assertCm(0, i);
+	}
+
+	public void clickCm(int... index) {
+		for (int idx : index) {
+			click(jq("@treerow:eq(" + idx + ") .z-treerow-checkable"));
+			waitResponse();
+		}
+	}
+
+	public void clickHdcm() {
+		click(jq("@treecol .z-treecol-checkable"));
+		waitResponse();
+	}
+
+	public void clickopen(int... index) {
+		for (int idx : index) {
+			click(jq(".z-tree-icon:eq(" + idx + ")"));
+			waitResponse();
+		}
+	}
+
+	public void assertCm(int state, int ... cmIndex) {
+		for (int idx : cmIndex) {
+			String trClassname = jq("@treerow:eq(" + idx + ")").toElement().get("className"),
+					iconClassname = jq("@treerow:eq(" + idx + ") .z-treerow-icon").toElement().get("className");
+			if (state == 2) {
+				assertTrue(trClassname.contains("z-treerow-partial"));
+				assertTrue(iconClassname.contains("z-icon-minus"));
+				assertFalse(trClassname.contains("z-treerow-selected"));
+				assertFalse(iconClassname.contains("z-icon-check"));
+			} else if (state == 1) {
+				assertTrue(trClassname.contains("z-treerow-selected"));
+				assertTrue(iconClassname.contains("z-icon-check"));
+				assertFalse(trClassname.contains("z-treerow-partial"));
+				assertFalse(iconClassname.contains("z-icon-minus"));
+			} else {
+				assertTrue(iconClassname.contains("z-icon-check"));
+				assertFalse(trClassname.contains("z-treerow-selected"));
+				assertFalse(trClassname.contains("z-treerow-partial"));
+				assertFalse(iconClassname.contains("z-icon-minus"));
+			}
+		}
+	}
+
+	public void assertHdcm(int state) {
+		JQuery hdcmClassname = jq(".z-treecol .z-treecol-checkable"),
+				iconClassname = jq(".z-treecol .z-treecol-checkable .z-treecol-icon");
+		if (state == 2) {
+			assertTrue(hdcmClassname.hasClass("z-treecol-partial"));
+			assertTrue(iconClassname.hasClass("z-icon-minus"));
+			assertFalse(hdcmClassname.hasClass("z-treecol-checked"));
+			assertFalse(iconClassname.hasClass("z-icon-check"));
+		} else if (state == 1) {
+			assertTrue(hdcmClassname.hasClass("z-treecol-checked"));
+			assertTrue(iconClassname.hasClass("z-icon-check"));
+			assertFalse(hdcmClassname.hasClass("z-treecol-partial"));
+			assertFalse(iconClassname.hasClass("z-icon-minus"));
+		} else {
+			assertTrue(iconClassname.hasClass("z-icon-check"));
+			assertFalse(hdcmClassname.hasClass("z-treecol-checked"));
+			assertFalse(hdcmClassname.hasClass("z-treecol-partial"));
+			assertFalse(iconClassname.hasClass("z-icon-minus"));
+		}
+	}
+}
diff --git a/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_2Test.java b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_2Test.java
new file mode 100644
index 00000000000..656fa33210c
--- /dev/null
+++ b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_2Test.java
@@ -0,0 +1,46 @@
+/* F100_ZK_3853_2Test.java
+
+        Purpose:
+                
+        Description:
+                
+        History:
+                Tue Jan 02 18:38:34 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.zats.test2;
+
+import org.junit.jupiter.api.Test;
+
+public class F100_ZK_3853_2Test extends F100_ZK_3853_1Test {
+
+	@Test
+	public void test() {
+		super.test();
+
+		clickCm(2, 9);
+
+		test_();
+
+		/* unbind model */
+		click(jq("@button"));
+		waitResponse();
+
+		/* when model is unbinded, header cm should be empty */
+		assertHdcm(0);
+
+		/* rebind model */
+		click(jq("@button"));
+		waitResponse();
+
+		test_();
+	}
+
+	private void test_() {
+		assertHdcm(2);
+		assertCm(2, 0, 4, 5, 8);
+		assertCm(1, 9);
+		assertCm(0, 1, 3, 6, 7, 10, 11, 12, 13);
+	}
+}
diff --git a/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_3Test.java b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_3Test.java
new file mode 100644
index 00000000000..f4aa21c371a
--- /dev/null
+++ b/zktest/src/test/java/org/zkoss/zktest/zats/test2/F100_ZK_3853_3Test.java
@@ -0,0 +1,132 @@
+/* F100_ZK_3853_3Test.java
+
+        Purpose:
+                
+        Description:
+                
+        History:
+                Tue Jan 02 19:34:54 CST 2024, Created by jamson
+
+Copyright (C) 2024 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.zats.test2;
+
+import org.junit.jupiter.api.Test;
+
+public class F100_ZK_3853_3Test extends F100_ZK_3853_1Test {
+
+	/*
+		mode 0: none
+		mode 1: checkmark
+		mode 2: multiple
+		mode 3: checkmark + multiple
+		mode 4: indeterminate ( + checkmark + multiple )
+	*/
+
+	@Test
+	public void none_to_indeterminate() {
+		connect();
+
+		click(jq("@treerow:eq(9)"));
+		waitResponse();
+		toggleIndeterminate(); // open
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 9);
+		assertCm(0, 0, 1, 2, 6, 7, 10, 11, 12, 13);
+	}
+
+	@Test
+	public void checkmark_to_indeterminate() {
+		connect();
+
+		toggleCheckmark(); // open
+		click(jq("@treerow:eq(9)"));
+		waitResponse();
+
+		toggleIndeterminate(); // open
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 9);
+		assertCm(0, 0, 1, 2, 6, 7, 10, 11, 12, 13);
+	}
+
+	@Test
+	public void multiple_to_indeterminate() {
+		connect();
+
+		toggleMultiple(); // open
+		click(jq("@treerow:eq(9)"));
+		waitResponse();
+
+		toggleIndeterminate(); // open
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 9);
+		assertCm(0, 0, 1, 2, 6, 7, 10, 11, 12, 13);
+	}
+
+	@Test
+	public void checkmark_and_multiple_to_indeterminate() {
+		connect();
+
+		toggleCheckmark(); // open
+		toggleMultiple(); // open
+
+		clickCm(2, 9);
+
+		toggleIndeterminate(); // open
+
+		assertHdcm(2);
+		assertCm(2, 0, 4, 5, 8);
+		assertCm(1, 2, 9);
+		assertCm(0, 1, 6, 7, 10, 11, 12, 13);
+	}
+
+	@Test
+	public void indeterminate_to_checkmark_and_multiple() {
+		connect();
+
+		toggleIndeterminate(); // open
+
+		click(jq("@treerow:eq(9)"));
+		waitResponse();
+
+		assertHdcm(2);
+		assertCm(2, 4, 5, 8);
+		assertCm(1, 9);
+		assertCm(0, 0, 1, 2, 6, 7, 10, 11, 12, 13);
+
+		toggleIndeterminate(); // close
+
+		assertHdcm(0);
+		for (int i = 0; i <= 13; ++i) {
+			if (i == 9) assertCm(1, 9);
+			else assertCm(0, i);
+		}
+	}
+
+	public void toggleCheckmark() {
+		click(jq("@button:eq(0)"));
+		waitResponse();
+	}
+
+	public void toggleMultiple() {
+		click(jq("@button:eq(1)"));
+		waitResponse();
+	}
+
+	public void toggleIndeterminate() {
+		click(jq("@button:eq(2)"));
+		waitResponse();
+	}
+
+	@Override
+	public void test() {
+		// don't run super's test()
+		// inherit just for the methods inside
+	}
+}
diff --git a/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java b/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
index 44db87594e8..abe7d812b80 100644
--- a/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
+++ b/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
@@ -38,9 +38,11 @@
 import org.zkoss.zul.event.TreeDataEvent;
 import org.zkoss.zul.event.TreeDataListener;
 import org.zkoss.zul.ext.Openable;
+import org.zkoss.zul.ext.PartialSelectable;
 import org.zkoss.zul.ext.Selectable;
 import org.zkoss.zul.ext.SelectionControl;
 import org.zkoss.zul.ext.TreeOpenableModel;
+import org.zkoss.zul.ext.TreePartialSelectableModel;
 import org.zkoss.zul.ext.TreeSelectableModel;
 
 /**
@@ -64,8 +66,8 @@
  * @author tomyeh
  * @since 3.0.0
  */
-public abstract class AbstractTreeModel<E> implements TreeModel<E>, TreeSelectableModel, TreeOpenableModel,
-		Selectable<E>, Openable<E>, java.io.Serializable, PageableModel {
+public abstract class AbstractTreeModel<E> implements TreeModel<E>, TreeSelectableModel, TreePartialSelectableModel,
+		TreeOpenableModel, Selectable<E>, PartialSelectable<E>, Openable<E>, java.io.Serializable, PageableModel {
 
 	private static final Logger log = LoggerFactory.getLogger(AbstractTreeModel.class);
 
@@ -77,9 +79,12 @@ public abstract class AbstractTreeModel<E> implements TreeModel<E>, TreeSelectab
 	private transient List<PagingListener> _pagingListeners = new ArrayList<PagingListener>();
 	/** The selection. */
 	protected Set<Path> _selection = new LinkedHashSet<Path>();
+	/** The partial selection. */
+	protected Set<Path> _partial =  new LinkedHashSet<Path>();
 	/** The open information. */
 	protected Set<Path> _opens = new LinkedHashSet<Path>();
 	private boolean _multiple;
+	private boolean _indeterminate;
 
 	private SelectionControl<E> _ctrl;
 
@@ -135,10 +140,12 @@ private void updatePath(TreeDataEvent event) {
 		case TreeDataEvent.INTERVAL_REMOVED:
 			internalDataChange(_opens, affectedPath, true);
 			internalDataChange(_selection, affectedPath, true);
+//			internalDataChange(_partial, affectedPath, true);
 			break;
 		case TreeDataEvent.INTERVAL_ADDED:
 			internalDataChange(_opens, affectedPath, false);
 			internalDataChange(_selection, affectedPath, false);
+//			internalDataChange(_partial, affectedPath, false);
 			break;
 		}
 	}
@@ -210,7 +217,7 @@ public void fireEvent(int evtType, int[] path, int indexFrom, int indexTo, int[]
 	/**
 	 * Fires a {@link TreeDataEvent} for all registered listener when selection
 	 * status has changed.
-	 * 
+	 *
 	 * @since 6.0.0
 	 */
 	protected void fireSelectionChanged(int[] path) {
@@ -319,15 +326,18 @@ public void setMultiple(boolean multiple) {
 			_multiple = multiple;
 			fireEvent(TreeDataEvent.MULTIPLE_CHANGED, null, -1, -1);
 
-			if (!multiple && _selection.size() > 1) {
-				final List<Path> sels = new LinkedList<Path>();
-				sels.addAll(_selection);
-				final Path sel = sels.remove(0);
-				_selection.clear();
-				_selection.add(sel);
+			if (!multiple) {
+				setIndeterminate(false);
+				if (_selection.size() > 1) {
+					final List<Path> sels = new LinkedList<Path>();
+					sels.addAll(_selection);
+					final Path sel = sels.remove(0);
+					_selection.clear();
+					_selection.add(sel);
 
-				for (final Path path : sels)
-					fireSelectionChanged(path.path);
+					for (final Path path : sels)
+						fireSelectionChanged(path.path);
+				}
 			}
 		}
 	}
@@ -338,6 +348,30 @@ public boolean isMultiple() {
 
 	// TreeSelectableModel
 
+	public void setIndeterminate(boolean indeterminate) {
+		if (_indeterminate != indeterminate) {
+			_indeterminate = indeterminate;
+			fireEvent(TreeDataEvent.INDETERMINATE_CHANGED, null, -1, -1);
+
+			if (indeterminate)
+				setMultiple(true);
+			if (!indeterminate && _partial.size() > 1) {
+				final List<Path> pars = new LinkedList<Path>();
+				pars.addAll(_partial);
+				final Path par = pars.remove(0);
+				_partial.clear();
+				_partial.add(par);
+
+				for (final Path path : pars)
+					fireSelectionChanged(path.path);
+			}
+		}
+	}
+
+	public boolean isIndeterminate() {
+		return _indeterminate;
+	}
+
 	public boolean addSelectionPath(int[] path) {
 		if (path != null && path.length > 0) {
 			final int[][] paths = new int[1][path.length];
@@ -434,6 +468,95 @@ public void clearSelection() {
 		}
 	}
 
+	// Tri-state partial
+
+	public boolean addPartialPath(int[] path) {
+		if (!isIndeterminate()) return false;
+		if (path != null && path.length > 0) {
+			final int[][] paths = new int[1][path.length];
+			paths[0] = path;
+			return addPartialPaths(paths);
+		}
+		return false;
+	}
+
+	public boolean addPartialPaths(int[][] paths) {
+		if (!isIndeterminate()) return false;
+		boolean added = false;
+		final int len = paths != null ? paths.length : 0;
+		for (int j = 0; j < len; ++j)
+			if (paths[j] != null) {
+				final Path path = new Path(paths[j]);
+				if (_partial.add(path)) {
+					added = true;
+					fireSelectionChanged(path.path);
+				}
+			}
+		return added;
+	}
+
+	public boolean removePartialPath(int[] path) {
+		if (!isIndeterminate()) return false;
+		if (path != null && path.length > 0) {
+			final int[][] paths = new int[1][path.length];
+			paths[0] = path;
+			return removePartialPaths(paths);
+		}
+		return false;
+	}
+
+	public boolean removePartialPaths(int[][] paths) {
+		if (!isIndeterminate()) return false;
+		boolean found = false;
+		final int len = paths != null ? paths.length : 0;
+		for (int j = 0; j < len && !_partial.isEmpty(); ++j) {
+			final Path path = new Path(paths[j]);
+			if (_partial.remove(path)) {
+				found = true;
+				fireSelectionChanged(path.path);
+			}
+		}
+		return found;
+	}
+
+	public boolean isPathPartial(int[] path) {
+		return isIndeterminate() && path != null && _partial.contains(new Path(path));
+	}
+
+	public int[] getPartialPath() {
+		return !isIndeterminate() || _partial.isEmpty() ? null : _partial.iterator().next().path;
+	}
+
+	public int[][] getPartialPaths() {
+		if (!isIndeterminate() || _partial.isEmpty())
+			return null;
+
+		final int[][] paths = new int[_partial.size()][];
+		int j = 0;
+		for (final Path path : _partial)
+			paths[j++] = path.path;
+		return paths;
+	}
+
+	public int getPartialCount() {
+		return _partial.size();
+	}
+
+	public boolean isPartialEmpty() {
+		return _partial.isEmpty();
+	}
+
+	public void clearPartial() {
+		if (!_partial.isEmpty()) {
+			final int[][] paths = getPartialPaths();
+			if (paths != null) {
+				_partial.clear();
+				for (int j = 0; j < paths.length; ++j)
+					fireSelectionChanged(paths[j]);
+			}
+		}
+	}
+
 	// TreeOpenableModel //
 
 	public boolean addOpenPath(int[] path) {
@@ -607,6 +730,58 @@ public boolean removeFromSelection(Object child) {
 		return false;
 	}
 
+	//PartialSelectable//
+
+
+	public Set<E> getPartial() {
+		if (!isIndeterminate()) return null;
+		final Set<E> partial = new LinkedHashSet<E>();
+		int[][] paths = getPartialPaths();
+		if (paths != null)
+			for (int i = 0; i < paths.length; i++)
+				partial.add(getChild(paths[i]));
+		return partial;
+	}
+
+	private boolean isPartialChanged(Collection<? extends E> partial) {
+		if (!isIndeterminate()) return false;
+
+		if (_partial.size() != partial.size())
+			return true;
+
+		for (final E e : partial)
+			if (!_partial.contains(e))
+				return true;
+		return false;
+	}
+
+	@SuppressWarnings("unchecked")
+	public boolean isPartial(Object child) {
+		if (!isIndeterminate()) return false;
+		final int[] path = getPath((E) child);
+		if (path != null && path.length > 0)
+			return isPathPartial(path);
+		return false;
+	}
+
+	public boolean addToPartial(E child) {
+		if (!isIndeterminate()) return false;
+		final int[] path = getPath(child);
+		if (path != null && path.length > 0)
+			return addPartialPath(path);
+		return false;
+	}
+
+	@SuppressWarnings("unchecked")
+
+	public boolean removeFromPartial(Object child) {
+		if (!isIndeterminate()) return false;
+		final int[] path = getPath((E) child);
+		if (path != null && path.length > 0)
+			return removePartialPath(path);
+		return false;
+	}
+
 	//Openable//
 
 	public Set<E> getOpenObjects() {
@@ -680,6 +855,7 @@ public Object clone() {
 		clone._pagingListeners = new ArrayList<PagingListener>();
 		clone._opens = new LinkedHashSet<Path>(_opens);
 		clone._selection = new LinkedHashSet<Path>(_selection);
+		clone._partial = new LinkedHashSet<Path>(_partial);
 		return clone;
 	}
 
diff --git a/zul/src/main/java/org/zkoss/zul/Tree.java b/zul/src/main/java/org/zkoss/zul/Tree.java
index 03b447e8144..31383a78502 100644
--- a/zul/src/main/java/org/zkoss/zul/Tree.java
+++ b/zul/src/main/java/org/zkoss/zul/Tree.java
@@ -34,6 +34,7 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
+import java.util.Queue;
 import java.util.Set;
 import java.util.Vector;
 
@@ -79,10 +80,12 @@
 import org.zkoss.zul.event.ZulEvents;
 import org.zkoss.zul.ext.Pageable;
 import org.zkoss.zul.ext.Paginal;
+import org.zkoss.zul.ext.PartialSelectable;
 import org.zkoss.zul.ext.Selectable;
 import org.zkoss.zul.ext.SelectionControl;
 import org.zkoss.zul.ext.Sortable;
 import org.zkoss.zul.ext.TreeOpenableModel;
+import org.zkoss.zul.ext.TreePartialSelectableModel;
 import org.zkoss.zul.ext.TreeSelectableModel;
 import org.zkoss.zul.impl.MeshElement;
 import org.zkoss.zul.impl.Utils;
@@ -205,13 +208,16 @@ public class Tree extends MeshElement {
 	private transient Treechildren _treechildren;
 	/** A list of selected items. */
 	private transient Set<Treeitem> _selItems;
+	/** A list of partial selected items. */
+	private transient Set<Treeitem> _partialItems;
 	/** The first selected item. */
 	private transient Treeitem _sel;
+	/** The first partial selected item. */
 	private transient Collection<Component> _heads;
 	private int _rows = 0;
 	/** The name. */
 	private String _name;
-	private boolean _multiple, _checkmark;
+	private boolean _multiple, _checkmark, _indeterminate;
 	private boolean _vflex;
 	private String _innerWidth = "100%";
 
@@ -228,6 +234,7 @@ public class Tree extends MeshElement {
 	 */
 	private transient Paging _paging;
 	private EventListener<Event> _pgListener, _pgImpListener, _modelInitListener;
+	private EventListener<SelectEvent> _indeterminateOnSelectListener;
 
 	private int _currentTop = 0; // since 5.0.8 scroll position
 	private int _currentLeft = 0;
@@ -257,6 +264,7 @@ public Tree() {
 
 	private void init() {
 		_selItems = new LinkedHashSet<Treeitem>(4);
+		_partialItems = new LinkedHashSet<Treeitem>(4);
 		_heads = new AbstractCollection<Component>() {
 			public int size() {
 				int sz = getChildren().size();
@@ -864,6 +872,8 @@ public boolean isCheckmark() {
 	public void setCheckmark(boolean checkmark) {
 		if (_checkmark != checkmark) {
 			_checkmark = checkmark;
+			if (!checkmark)
+				setIndeterminate(false);
 			smartUpdate("checkmark", checkmark);
 		}
 	}
@@ -969,13 +979,16 @@ public boolean isMultiple() {
 	public void setMultiple(boolean multiple) {
 		if (_multiple != multiple) {
 			_multiple = multiple;
-			if (!_multiple && _selItems.size() > 1) {
-				final Treeitem item = getSelectedItem();
-				for (Iterator<Treeitem> it = _selItems.iterator(); it.hasNext();) {
-					final Treeitem ti = it.next();
-					if (ti != item) {
-						ti.setSelectedDirectly(false);
-						it.remove();
+			if (!_multiple) {
+				setIndeterminate(false);
+				if (_selItems.size() > 1) {
+					final Treeitem item = getSelectedItem();
+					for (Iterator<Treeitem> it = _selItems.iterator(); it.hasNext();) {
+						final Treeitem ti = it.next();
+						if (ti != item) {
+							ti.setSelectedDirectly(false);
+							it.remove();
+						}
 					}
 				}
 				//No need to update selId because z.multiple will do the job
@@ -986,6 +999,60 @@ public void setMultiple(boolean multiple) {
 		}
 	}
 
+	/** Returns whether indeterminate selection mode is activated.
+	 * At the same time, setCheckmark(true) and setMultiple(true) will be called automatically.
+	 * Once this mode is on, setCheckmark(false) and setMultiple(false) will also set indeterminate to false.
+	 * <p>Default: false.
+	 * @since 10.0.0
+	 */
+	public boolean isIndeterminate() {
+		return _indeterminate;
+	}
+
+	/** Returns whether indeterminate selection mode is activated.
+	 * At the same time, setCheckmark(true) and setMultiple(true) will be called automatically.
+	 * Once this mode is on, setCheckmark(false) and setMultiple(false) will also set indeterminate to false.
+	 * <p>Notice that, if a model is assigned, it will change the model's
+	 * state (by {@link org.zkoss.zul.ext.PartialSelectable#setIndeterminate}).
+	 * @since 10.0.0
+	 */
+	public void setIndeterminate(boolean indeterminate) {
+		if (_indeterminate != indeterminate) {
+			_indeterminate = indeterminate;
+			if (_model != null)
+				((TreePartialSelectableModel) _model).setIndeterminate(indeterminate);
+			smartUpdate("indeterminate", _indeterminate);
+
+			if (_indeterminate) {
+				setCheckmark(true);
+				setMultiple(true);
+				_partialItems = new LinkedHashSet<Treeitem>(4);
+
+				// init indeterminate state FIXME: opt TC
+				Set<Treeitem> currentSelectedItmes = new LinkedHashSet<>(_selItems);
+				for (Treeitem item : currentSelectedItmes)
+					updInd(item);
+
+				// ON_SELECT indeterminate mode event listener
+				if (_indeterminateOnSelectListener == null)
+					_indeterminateOnSelectListener = event -> {
+						if (event.getReference() instanceof Treeitem)
+							updInd((Treeitem) event.getReference());
+					};
+				addEventListener(Events.ON_SELECT, _indeterminateOnSelectListener);
+			} else {
+				// unlike selection's removal leave 1 selection, partial state has to ALL removed
+				if (!_partialItems.isEmpty()) {
+					for (Iterator<Treeitem> it = _partialItems.iterator(); it.hasNext();) {
+						it.next();
+						it.remove();
+					}
+				}
+				removeEventListener(Events.ON_SELECT, _indeterminateOnSelectListener);
+			}
+		}
+	}
+
 	/** Sets the active page in which the specified item is.
 	 * The active page will become the page that contains the specified item.
 	 *
@@ -1177,6 +1244,19 @@ private void smartUpdateSelection() {
 		smartUpdate("chgSel", sb.toString());
 	}
 
+	/** Note: we have to update all partial selection at once, since addItemToPartial
+	 * and removeItemFromPartial might be called interchangeably.
+	 */
+	private String getResponsePartialData() {
+		final StringBuffer sb = new StringBuffer(80);
+		for (Treeitem item : _partialItems) {
+			if (sb.length() > 0)
+				sb.append(',');
+			sb.append(item.getUuid());
+		}
+		return sb.toString();
+	}
+
 	/** If the specified item is selected, it is deselected.
 	 * If it is not selected, it is selected. Other items in the tree
 	 * that are selected are not affected, and retain their selected state.
@@ -1256,6 +1336,38 @@ public void clear() {
 			_treechildren.getChildren().clear();
 	}
 
+	private void addItemToPartial(Treeitem item) {
+		if (item.getTree() != this)
+			throw new UiException("Not a child: " + item);
+		if (!_indeterminate)
+			return;
+		_partialItems.add(item);
+		smartUpdate("chgPartial", getResponsePartialData());
+	}
+
+	private void removeItemFromPartial(Treeitem item) {
+		if (item.getTree() != this)
+			throw new UiException("Not a child: " + item);
+		if (!_indeterminate)
+			return;
+		_partialItems.remove(item);
+		smartUpdate("chgPartial", getResponsePartialData());
+	}
+
+	/** Returns all partial selected items.
+	 * @since 10.0.0
+	 */
+	public Set<Treeitem> getPartialItems() {
+		return Collections.unmodifiableSet(_partialItems);
+	}
+
+	/** Returns the number of items being partial selected.
+	 * @since 10.0.0
+	 */
+	public int getPartialCount() {
+		return _partialItems.size();
+	}
+
 	//-- Component --//
 	public String getZclass() {
 		return _zclass == null ? "z-tree" : _zclass;
@@ -1615,8 +1727,15 @@ private void onTreeDataChange(TreeDataEvent event) {
 			}
 			return;
 		case TreeDataEvent.SELECTION_CHANGED:
-			if (target instanceof Treeitem)
+			if (target instanceof Treeitem) {
 				((Treeitem) target).setSelected(((TreeSelectableModel) _model).isPathSelected(path));
+				if (_indeterminate) {
+					if (((TreePartialSelectableModel) _model).isPathPartial(path))
+						addItemToPartial((Treeitem) target);
+					else
+						removeItemFromPartial((Treeitem) target);
+				}
+			}
 			return;
 		case TreeDataEvent.OPEN_CHANGED:
 			if (_model instanceof TreeOpenableModel) {
@@ -1627,6 +1746,9 @@ private void onTreeDataChange(TreeDataEvent event) {
 		case TreeDataEvent.MULTIPLE_CHANGED:
 			setMultiple(((TreeSelectableModel) _model).isMultiple());
 			return;
+		case TreeDataEvent.INDETERMINATE_CHANGED:
+			setIndeterminate(((TreePartialSelectableModel) _model).isIndeterminate());
+			return;
 		}
 
 		/*
@@ -1705,6 +1827,8 @@ private void onTreeDataInsert(Component parent, Object node, int index) {
 					// Note: we don't use index >= size(); reason: it detects bug
 					siblings.isEmpty() || index == siblings.size() ? null : (Treeitem) siblings.get(index));
 			renderChangedItem(newTi, _model.getChild(node, index));
+			if (_indeterminate)
+				updInd(newTi);
 		}
 	}
 
@@ -1715,7 +1839,13 @@ private void onTreeDataRemoved(Component parent, Object node, int index) {
 		final Treechildren tc = treechildrenOf(parent);
 		final List<? extends Component> items = tc.getChildren();
 		if (items.size() > index) {
-			((Treeitem) items.get(index)).detach();
+			Treeitem target = (Treeitem) items.get(index);
+			target.detach();
+			if (_indeterminate) {
+				if (parent instanceof Treeitem)
+					updActNodesInd(((Treeitem) parent).getValue());
+				updHdcmInd();
+			}
 		} else if (!(parent instanceof Treeitem) || ((Treeitem) parent).isLoaded()) {
 			tc.detach();
 		}
@@ -1859,6 +1989,7 @@ public void setModel(TreeModel<?> model) {
 			_model = null;
 			if (_treechildren != null)
 				_treechildren.detach();
+			_partialItems.clear();
 			//don't call getItems().clear(), since it readonly
 			//bug# 3095453: tree can't expand if model is set in button onClick
 			smartUpdate("model", false);
@@ -2021,8 +2152,16 @@ private void renderChildren0(Renderer renderer, Treechildren parent, Treeitem ti
 		if (_model instanceof TreeSelectableModel) {
 			TreeSelectableModel model = (TreeSelectableModel) _model;
 			if (!model.isSelectionEmpty() && getSelectedCount() != model.getSelectionCount()
-					&& model.isPathSelected(path = getPath0(parent, i)))
+					&& model.isPathSelected(path = getPath0(parent, i))) {
 				addItemToSelection(ti);
+			}
+		}
+		if (_indeterminate && _model instanceof TreePartialSelectableModel) {
+			TreePartialSelectableModel model = (TreePartialSelectableModel) _model;
+			if (!model.isPartialEmpty() && getPartialCount() != model.getPartialCount()
+					&& model.isPathPartial(path = getPath0(parent, i))) {
+				addItemToPartial(ti);
+			}
 		}
 		if (_model instanceof Selectable) {
 			Selectable smodel = (Selectable) _model;
@@ -2594,6 +2733,7 @@ protected void renderProperties(org.zkoss.zk.ui.sys.ContentRenderer renderer) th
 
 		render(renderer, "multiple", isMultiple());
 		render(renderer, "checkmark", isCheckmark());
+		render(renderer, "indeterminate", isIndeterminate());
 		render(renderer, "vflex", isVflex());
 
 		if (_model != null) {
@@ -2606,6 +2746,7 @@ protected void renderProperties(org.zkoss.zk.ui.sys.ContentRenderer renderer) th
 				}
 			}
 		}
+		render(renderer, "chgPartial", getResponsePartialData());
 
 		if (_nonselTags != null)
 			renderer.render("nonselectableTags", _nonselTags);
@@ -2780,6 +2921,7 @@ public PropertyAccess getPropertyAccess(String prop) {
 	@SuppressWarnings({ "rawtypes", "unchecked" })
 	public void service(org.zkoss.zk.au.AuRequest request, boolean everError) {
 		final String cmd = request.getCommand();
+
 		boolean isSelModel = _model instanceof Selectable;
 		if (cmd.equals(Events.ON_SELECT)) {
 			Desktop desktop = request.getDesktop();
@@ -2912,14 +3054,23 @@ public void service(org.zkoss.zk.au.AuRequest request, boolean everError) {
 			final Map<String, Object> data = request.getData();
 			_anchorTop = AuRequests.getInt(data, "top", 0);
 			_anchorLeft = AuRequests.getInt(data, "left", 0);
-		} else if (cmd.equals(Events.ON_CHECK_SELECT_ALL) && isSelModel) {
+		} else if (cmd.equals(Events.ON_CHECK_SELECT_ALL)) {
 			CheckEvent evt = CheckEvent.getCheckEvent(request);
-			final Selectable<Object> selectableModel = (Selectable<Object>) _model;
-			SelectionControl control = selectableModel.getSelectionControl();
-			if (control == null)
-				throw new IllegalStateException(
-						"SelectionControl cannot be null, please implement SelectionControl interface for SelectablModel");
-			control.setSelectAll(evt.isChecked());
+			if (isSelModel) {
+				final Selectable<Object> selectableModel = (Selectable<Object>) _model;
+				SelectionControl control = selectableModel.getSelectionControl();
+				if (control == null)
+					throw new IllegalStateException(
+							"SelectionControl cannot be null, please implement SelectionControl interface for SelectablModel");
+				control.setSelectAll(evt.isChecked());
+			}
+			if (_indeterminate) { // indeterminate mode select all
+				// no matter is select-all or clear-all, partial state should all clear
+				Set<Treeitem> partials = new LinkedHashSet(getPartialItems());
+				for (Treeitem item : partials)
+					removeItemFromPartial(item);
+				smartUpdate("treecolIcon", evt.isChecked() ? 1 : 0);
+			}
 			Events.postEvent(evt);
 		} else if (cmd.equals("onUpdateSelectAll") && isSelModel) {
 			final Selectable<Object> selectableModel = (Selectable<Object>) _model;
@@ -3044,4 +3195,139 @@ public void onAfterRender() {
 			}
 		}
 	}
+
+	/** update all affected treeitems' or treenodes' indeterminate state */
+	private void updInd(Treeitem item) {
+		boolean isSelected = item.isSelected();
+		if (_model instanceof PartialSelectable && _model instanceof TreePartialSelectableModel) {
+			updDcdNodesInd(item.getValue(), isSelected);
+			updActNodesInd(((TreeNode) (item.getValue())).getParent());
+		} else {
+			updDcdItemsInd(item, isSelected);
+			updActItemsInd(item.getParentItem());
+		}
+		updHdcmInd();
+	}
+
+	/** update descendant treeitems indeterminate state */
+	private void updDcdItemsInd(Treeitem item, boolean isSelected) {
+		Queue<Treeitem> q = new LinkedList<>();
+		q.offer(item);
+		while (!q.isEmpty()) {
+			Treeitem cur = q.remove();
+			removeItemFromSelection(cur);
+			removeItemFromPartial(cur);
+			if (isSelected)
+				addItemToSelection(cur);
+			if (cur.getTreechildren() != null
+					&& cur.getTreechildren().getItems() != null
+					&& !cur.getTreechildren().getItems().isEmpty())
+				q.addAll(cur.getTreechildren().getItems());
+		}
+	}
+
+	/** update ancestor treeitems indeterminate state */
+	private void updActItemsInd(Treeitem item) {
+		Treeitem cur = item;
+		while (cur != null) {
+			int selectedChild = 0,
+				partialChild = 0,
+				numberOfChild = 0;
+			if (cur.getTreechildren() != null
+					&& cur.getTreechildren().getItems() != null
+					&& !cur.getTreechildren().getItems().isEmpty())
+				for (Treeitem child : cur.getTreechildren().getItems()) {
+					if (_selItems.contains(child))
+						selectedChild++;
+					if (_partialItems.contains(child))
+						partialChild++;
+					numberOfChild++;
+				}
+			removeItemFromSelection(cur);
+			removeItemFromPartial(cur);
+			if (selectedChild == numberOfChild)
+				addItemToSelection(cur);
+			else if (selectedChild + partialChild != 0)
+				addItemToPartial(cur);
+			cur = cur.getParentItem();
+		}
+	}
+
+	/** update descendant treenodes indeterminate state */
+	private void updDcdNodesInd(TreeNode node, boolean isSelected) {
+		// in TreeNode update, we don't need to update icon, it'll update when model update to component
+		AbstractTreeModel model = (AbstractTreeModel) _model;
+
+		Queue<TreeNode> q = new LinkedList<>();
+		q.offer(node);
+		while (!q.isEmpty()) {
+			TreeNode cur = q.remove();
+			model.removeFromSelection(cur);
+			model.removeFromPartial(cur);
+			if (isSelected)
+				model.addToSelection(cur);
+			if (cur.getChildren() != null && !cur.getChildren().isEmpty())
+				q.addAll(cur.getChildren());
+		}
+	}
+
+	/** update ancestor treenodes indeterminate state */
+	private void updActNodesInd(TreeNode node) {
+		// in TreeNode update, we don't need to update icon, it'll update when model update to component
+		AbstractTreeModel model = (AbstractTreeModel) _model;
+
+		TreeNode cur = node;
+		while (cur != null) {
+			int selectedChild = 0,
+				partialChild = 0,
+				numberOfChild = 0;
+			if (cur.getChildren() != null && !cur.getChildren().isEmpty())
+				for (Object child : cur.getChildren()) {
+					if (model.isSelected(child))
+						selectedChild++;
+					if (model.isPartial(child))
+						partialChild++;
+					numberOfChild++;
+				}
+			model.removeFromSelection(cur);
+			model.removeFromPartial(cur);
+			if (selectedChild == numberOfChild)
+				model.addToSelection(cur);
+			else if (selectedChild + partialChild != 0)
+				model.addToPartial(cur);
+			cur = cur.getParent();
+		}
+	}
+
+	/** udpate header checkmark indeterminate state */
+	private void updHdcmInd() {
+		if (this._treecols != null && this._treecols.getFirstChild() instanceof Treecol) {
+			boolean treecolShouldBePartial = false;
+			int numberOfChild = 0,
+				selectedChild = 0;
+			for (Component cur = this._treechildren.getFirstChild(); cur != null; cur = cur.getNextSibling()) {
+				if (cur instanceof Treeitem) {
+					numberOfChild++;
+					Treeitem curItem = (Treeitem) cur;
+					if (_partialItems.contains(curItem)) {
+						// if 1 child is partial,
+						// then treecol should be partial, break directly
+						treecolShouldBePartial = true;
+						break;
+					} else {
+						if (curItem.isSelected())
+							selectedChild++;
+						else if (selectedChild != 0) {
+							// if current is empty, and at least 1 selected found,
+							// then treecol should be partial, break directly
+							treecolShouldBePartial = true;
+							break;
+						}
+					}
+				}
+			}
+			treecolShouldBePartial = treecolShouldBePartial || (selectedChild != numberOfChild && selectedChild != 0);
+			smartUpdate("treecolIcon", treecolShouldBePartial ? 2 : selectedChild == numberOfChild ? 1 : 0);
+		}
+	}
 }
diff --git a/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java b/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
index 4e5fbe5ed78..89ad8335a14 100644
--- a/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
+++ b/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
@@ -41,6 +41,10 @@ public class TreeDataEvent {
 	 * @since 6.0.0
 	 */
 	public static final int MULTIPLE_CHANGED = 6;
+	/** Identified the state of {@link org.zkoss.zul.AbstractTreeModel#isIndeterminate()} is changed.
+	 * @since 10.0.0
+	 */
+	public static final int INDETERMINATE_CHANGED = 8;
 	/**
 	 * Identified the state that Component's client update to be disabled
 	 * @since 8.0.0
@@ -64,12 +68,12 @@ public class TreeDataEvent {
 	 *
 	 * @param type one of {@link #CONTENTS_CHANGED},
 	 * {@link #INTERVAL_ADDED}, {@link #INTERVAL_REMOVED}, {@link #SELECTION_CHANGED},
-	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}.
+	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}.
 	 * @param nodePath the path of the affected node.
 	 * If {@link #CONTENTS_CHANGED}, {@link #INTERVAL_ADDED} or {@link #INTERVAL_REMOVED},
 	 * it is the parent node. If {@link #SELECTION_CHANGED} or {@link #OPEN_CHANGED},
 	 * it is the node being selected or opened.
-	 * If {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}, it is null.
+	 * If {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}, it is null.
 	 * @param indexFrom the lower index of the change range
 	 * @param indexTo the upper index of the change range
 	 */
@@ -87,12 +91,12 @@ public TreeDataEvent(TreeModel model, int type, int[] nodePath, int indexFrom, i
 	 *
 	 * @param type one of {@link #CONTENTS_CHANGED},
 	 * {@link #INTERVAL_ADDED}, {@link #INTERVAL_REMOVED}, {@link #SELECTION_CHANGED},
-	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}.
+	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}.
 	 * @param nodePath the path of the affected node.
 	 * If {@link #CONTENTS_CHANGED}, {@link #INTERVAL_ADDED} or {@link #INTERVAL_REMOVED},
 	 * it is the parent node. If {@link #SELECTION_CHANGED} or {@link #OPEN_CHANGED},
 	 * it is the node being selected or opened.
-	 * If {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}, it is null.
+	 * If {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}, it is null.
 	 * @param indexFrom the lower index of the change range
 	 * @param indexTo the upper index of the change range
 	 * @param affectedPath the path to be removed or added
@@ -111,12 +115,12 @@ public TreeDataEvent(TreeModel model, int type, int[] nodePath, int indexFrom, i
 	 *
 	 * @param type one of {@link #CONTENTS_CHANGED},
 	 * {@link #INTERVAL_ADDED}, {@link #INTERVAL_REMOVED}, {@link #SELECTION_CHANGED},
-	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}.
+	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}.
 	 * @param nodePath the path of the affected node.
 	 * If {@link #CONTENTS_CHANGED}, {@link #INTERVAL_ADDED} or {@link #INTERVAL_REMOVED},
 	 * it is the parent node. If {@link #SELECTION_CHANGED} or {@link #OPEN_CHANGED},
 	 * it is the node being selected or opened.
-	 * If {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}, it is null.
+	 * If {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}, it is null.
 	 * @param indexFrom the lower index of the change range
 	 * @param indexTo the upper index of the change range
 	 * @param affectedPaths the paths to be removed or added
@@ -154,7 +158,7 @@ public int getType() {
 	 * If {@link #CONTENTS_CHANGED}, {@link #INTERVAL_ADDED} or {@link #INTERVAL_REMOVED},
 	 * it is the parent node. If {@link #SELECTION_CHANGED} or {@link #OPEN_CHANGED},
 	 * it is the node being selected or opened.
-	 * If {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}, it is null.
+	 * If {@link #STRUCTURE_CHANGED}, {@link #MULTIPLE_CHANGED} or {@link #INDETERMINATE_CHANGED}, it is null.
 	 * @return the parent node that one of its children being modified 
 	 */
 	public int[] getPath() {
diff --git a/zul/src/main/java/org/zkoss/zul/ext/PartialSelectable.java b/zul/src/main/java/org/zkoss/zul/ext/PartialSelectable.java
new file mode 100644
index 00000000000..924087caa39
--- /dev/null
+++ b/zul/src/main/java/org/zkoss/zul/ext/PartialSelectable.java
@@ -0,0 +1,82 @@
+/* PartialSelectable.java
+
+        Purpose:
+                
+        Description:
+                
+        History:
+                Fri Dec 22 12:06:40 CST 2023, Created by jamson
+
+Copyright (C) 2023 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zul.ext;
+
+import java.util.Set;
+
+import org.zkoss.zul.Tree;
+import org.zkoss.zul.TreeModel;
+
+/**
+ * Indicate a partial selectable collection or component. Generally used with
+ * {@link Selectable} {@link TreePartialSelectableModel} {@link TreeSelectableModel}
+ * {@link TreeModel} and {@link Tree}.
+ * @author Jamson Chan
+ * @since 10.0.0
+ */
+public interface PartialSelectable<E> {
+
+	/**
+	 * Returns the current partial selection.
+	 * It is readonly. Don't modify it directly
+	 * @return the current partial selection.
+	 */
+	public Set<E> getPartial();
+
+	/**
+	 * Returns whether an object is partially selected.
+	 */
+	public boolean isPartial(Object obj);
+
+	/**
+	 * Returns true if the partial selection is currently empty.
+	 */
+	public boolean isPartialEmpty();
+
+	/**
+	 * Add the specified object into partial selection.
+	 * <p>If this represents a change to the
+	 * current partial selection then notify each TreeDataListener, including UI.
+	 * @param obj the object to be as partial selection.
+	 * @return true if it is added successfully; false if <code>obj</code>
+	 * is not part of the data, or was already partial selected.
+	 */
+	public boolean addToPartial(E obj);
+
+	/**
+	 * Remove the specified object from partial selection.
+	 * <p>If this represents a change to the
+	 * current partial selection then notify each TreeDataListener, including UI.
+	 * @param obj the object to be remove from partial selection.
+	 * @return whether it is removed successfully
+	 */
+	public boolean removeFromPartial(Object obj);
+
+	/**
+	 * Change the partial selection to the empty set.
+	 * <p>If this represents a change to the
+	 * current partial selection then notify each ListDataListener, including UI.
+	 */
+	public void clearPartial();
+
+	/**
+	 * Sets the partial selection mode to be multiple.
+	 */
+	public void setIndeterminate(boolean multiple);
+
+	/**
+	 * Returns whether the current partial selection mode is multiple.
+	 * @see #setIndeterminate
+	 */
+	public boolean isIndeterminate();
+
+}
diff --git a/zul/src/main/java/org/zkoss/zul/ext/TreePartialSelectableModel.java b/zul/src/main/java/org/zkoss/zul/ext/TreePartialSelectableModel.java
new file mode 100644
index 00000000000..51b6d1d4fb2
--- /dev/null
+++ b/zul/src/main/java/org/zkoss/zul/ext/TreePartialSelectableModel.java
@@ -0,0 +1,113 @@
+/* PartialSelectable.java
+
+        Purpose:
+
+        Description:
+
+        History:
+                Fri Dec 22 12:05:16 CST 2023, Created by jamson
+
+Copyright (C) 2023 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zul.ext;
+
+import org.zkoss.zul.Tree;
+import org.zkoss.zul.TreeModel;
+
+/**
+ * Indicate a tree model that supports selection. It is typically used with
+ * {@link TreeSelectableModel} {@link TreeModel} and {@link Tree}.
+ *
+ * @author Jamson Chan
+ * @since 10.0.0
+ */
+public interface TreePartialSelectableModel {
+
+	/**
+	 * Sets the selection mode to be indeterminate.
+	 */
+	public void setIndeterminate(boolean multiple);
+
+	/**
+	 * Returns whether the current selection mode is indeterminate.
+	 *
+	 * @see #setIndeterminate
+	 */
+	public boolean isIndeterminate();
+
+	/**
+	 * Adds path to the current partial selection. If path is not currently in the
+	 * selection the TreeDataListeners are notified. This has no effect if
+	 * <code>path</code> is null.
+	 *
+	 * @param path the new path to add to the current partial selection
+	 * @return whether it is added successfully
+	 */
+	public boolean addPartialPath(int[] path);
+
+	/**
+	 * Adds paths to the current partial selection. If any of the paths in paths are not
+	 * currently in the partial selection the TreeDataListeners are notified. This has
+	 * no effect if <code>paths</code> is null.
+	 *
+	 * @param paths the new paths to add to the current partial selection
+	 * @return whether it is added successfully
+	 */
+	public boolean addPartialPaths(int[][] paths);
+
+	/**
+	 * Removes path from the partial selection. If path is in the partial selection The
+	 * TreeDataListeners are notified. This has no effect if <code>path</code>
+	 * is null.
+	 *
+	 * @param path
+	 *            the path to remove from the partial selection
+	 * @return true if it was unselected successfully
+	 */
+	public boolean removePartialPath(int[] path);
+
+	/**
+	 * Removes paths from the partial selection. If any of the paths in
+	 * <code>paths</code> are in the partial selection, the TreeDataListeners are
+	 * notified. This method has no effect if <code>paths</code> is null.
+	 *
+	 * @param paths
+	 *            the path to remove from the partial selection
+	 * @return true if one of the paths was unselected successfully
+	 */
+	public boolean removePartialPaths(int[][] paths);
+
+	/**
+	 * Returns true if the path, <code>path</code>, is in the current partial selection.
+	 */
+	public boolean isPathPartial(int[] path);
+
+	/**
+	 * Returns true if the partial selection is currently empty.
+	 */
+	public boolean isPartialEmpty();
+
+	/**
+	 * Empties the current partial selection. If this represents a change in the current
+	 * partial selection, the partial selection listeners are notified.
+	 */
+	public void clearPartial();
+
+	/**
+	 * Returns the first path in the partial selection. How first is defined is up to
+	 * implementors.
+	 */
+	public int[] getPartialPath();
+
+	/**
+	 * Returns the paths in the partial selection. This will return null (or an empty
+	 * array) if nothing is currently partial selected or indeterminate mode is off.
+	 */
+	public int[][] getPartialPaths();
+
+	/**
+	 * Returns the number of paths that are partially selected.
+	 */
+	public int getPartialCount();
+
+}
diff --git a/zul/src/main/resources/metainfo/xml/zul.xsd b/zul/src/main/resources/metainfo/xml/zul.xsd
index c37ab370173..cab08198606 100644
--- a/zul/src/main/resources/metainfo/xml/zul.xsd
+++ b/zul/src/main/resources/metainfo/xml/zul.xsd
@@ -3448,6 +3448,7 @@
 		<xs:attribute name="paginal" type="xs:string" use="optional" />
 		<xs:attribute name="onPaging" type="xs:string" use="optional" />
 		<xs:attribute name="multiple" type="booleanType" use="optional" />
+		<xs:attribute name="indeterminate" type="booleanType" use="optional" />
 		<xs:attribute name="selectedItem" type="xs:string" use="optional" />
 		<xs:attribute name="model" type="xs:string" use="optional" />
 		<xs:attribute name="itemRenderer" type="xs:string" use="optional" />
diff --git a/zul/src/main/resources/web/js/zul/sel/Tree.ts b/zul/src/main/resources/web/js/zul/sel/Tree.ts
index 32395d311cc..19bdb3cd417 100644
--- a/zul/src/main/resources/web/js/zul/sel/Tree.ts
+++ b/zul/src/main/resources/web/js/zul/sel/Tree.ts
@@ -44,6 +44,15 @@ export class Tree extends zul.sel.SelectWidget {
 	_fixhdwcnt?: number; // zul.sel.Treeitem.prototype.setOpen
 	/** @internal */
 	_fixhdoldwd?: number; // zul.sel.Treeitem.prototype.setOpen
+	/** @internal */
+	_indeterminate?: boolean;
+	/** @internal */
+	_partialItems!: zul.sel.Treeitem[]; // to remove all partial icon when indeterminate mode disable
+
+	constructor() {
+		super();
+		this._partialItems = [];
+	}
 
 	/** @internal */
 	override unbind_(skipper?: zk.Skipper, after?: CallableFunction[], keepRod?: boolean): void {
@@ -51,6 +60,44 @@ export class Tree extends zul.sel.SelectWidget {
 		super.unbind_(skipper, after, keepRod);
 	}
 
+	override removeChild(child: zk.Widget, ignoreDom?: boolean): boolean {
+		// in order to remove treecol partial icon in indeterminate mode when detach
+		if (this._indeterminate && child instanceof zul.sel.Treechildren)
+			this.setTreecolIcon(0);
+		return super.removeChild(child, ignoreDom);
+	}
+
+	/**
+	 * Sets the selection state of treecol's icon.
+	 * <p>This method is called from the server, do NOT set it manually!
+	 * @param treecolIcon - a number among 0, 1, and 2, represents the
+	 * selection state to which treecol should be replaced.
+	 * <p>0: unselected, no icon.
+	 * <p>1: selected, check icon.
+	 * <p>2: partial selected, minus icon.
+	 */
+	setTreecolIcon(treecolIcon: number): this { // called from server, do NOT set it manually!
+		if ((0 <= treecolIcon || treecolIcon <= 2) && this.treecols?.firstChild != null) {
+			const tc = this.treecols.firstChild,
+				tcuuid = tc.uuid,
+				cm = jq(tc.$n('cm')),
+				icon = jq('#' + tcuuid + '-cm .z-treecol-icon');
+
+			cm.removeClass('z-treecol-checked').removeClass('z-treecol-partial');
+			icon.removeClass('z-icon-minus');
+
+			if (treecolIcon === 2) {
+				cm.addClass('z-treecol-partial');
+				icon.removeClass('z-icon-check').addClass('z-icon-minus');
+			} else {
+				icon.addClass('z-icon-check');
+				if (treecolIcon === 1)
+					cm.addClass('z-treecol-checked');
+			}
+		}
+		return this;
+	}
+
 	override onSize(): void {
 		super.onSize();
 		var self = this,
@@ -377,6 +424,44 @@ export class Tree extends zul.sel.SelectWidget {
 		return this.treechildren != null ? this.treechildren.getItemCount(opts) : 0;
 	}
 
+	override setMultiple(multiple: boolean, opts?: Record<string, boolean>): this {
+		if (this._multiple && !multiple)
+			this.setIndeterminate(false);
+		return super.setMultiple(multiple, opts);
+	}
+
+	/**
+	 * @returns whether indeterminate mode is enabled.
+	 */
+	isIndeterminate(): boolean {
+		return !!this._indeterminate;
+	}
+
+	/**
+	 * Sets whether indeterminate mode is enabled.
+	 */
+	setIndeterminate(indeterminate: boolean, opts?: Record<string, boolean>): this {
+		const o = this._indeterminate;
+		this._indeterminate = indeterminate;
+
+		if (o !== indeterminate || opts?.force) {
+			if (!this._indeterminate)
+				this.setTreecolIcon(0);
+				if (this._partialItems.length)
+					while (this._partialItems.length) {
+						const item = this._partialItems.pop();
+						if (item)
+							this._changePartial(item, false);
+					}
+			else {
+				this.setMultiple(true);
+				this.setCheckmark(true);
+				this._partialItems = [];
+			}
+		}
+		return this;
+	}
+
 	/** @internal */
 	override _doLeft(row: zul.sel.Treeitem): void {
 		if (row.isOpen()) {
@@ -437,6 +522,38 @@ export class Tree extends zul.sel.SelectWidget {
 		}
 		return false;
 	}
+
+	setChgPartial(chgPartial: string): this { //called from the server, do NOT set it manually!
+		var pars = {};
+		for (var j = 0; ;) {
+			var k = chgPartial.indexOf(',', j),
+				s = (k >= 0 ? chgPartial.substring(j, k) : chgPartial.substring(j)).trim();
+			if (s) pars[s] = true;
+			if (k < 0) break;
+			j = k + 1;
+		}
+
+		// widget iterator data will init after mount, so update partial state later
+		zk.afterMount(() => {
+			for (var it = this.getBodyWidgetIterator(), w: zul.sel.Treeitem | undefined; (w = it.next());)
+				this._changePartial(w, pars[w.uuid] == true);
+		});
+		return this;
+	}
+
+	/* Changes the partial selected status of an item without affecting other items
+	 * and return true if the status is really changed.
+	 */
+	/** @internal */
+	_changePartial(item: zul.sel.Treeitem, toPar: boolean): boolean {
+		const changed = item.isPartial() != toPar;
+		if (changed) {
+			if (toPar) this._partialItems.push(item);
+			else this._partialItems.$remove(item);
+			item._setPartialDirectly(toPar);
+		}
+		return changed;
+	}
 }
 
 /**
diff --git a/zul/src/main/resources/web/js/zul/sel/Treecell.ts b/zul/src/main/resources/web/js/zul/sel/Treecell.ts
index e7a206f1702..e84270109ec 100644
--- a/zul/src/main/resources/web/js/zul/sel/Treecell.ts
+++ b/zul/src/main/resources/web/js/zul/sel/Treecell.ts
@@ -201,8 +201,10 @@ export class Treecell extends zul.LabelImageWidget<HTMLTableCellElement> {
 				if (tree.isCheckmark()) {
 					var chkable = item.isSelectable(),
 						multi = tree.isMultiple(),
+						indet = tree.isIndeterminate(),
+						isPartial = this.parent?.parent?.isPartial(),
 						cmCls = multi ? item.$s('checkbox') : item.$s('radio'),
-						ckCls = multi ? ' z-icon-check' : ' z-icon-radio';
+						ckCls = multi ? indet && isPartial ? ' z-icon-minus' : ' z-icon-check' : ' z-icon-radio';
 					out.push('<span id="', /*safe*/ this.parent!.uuid, '-cm" class="',
 							item.$s('checkable'), ' ', /*safe*/ cmCls);
 
diff --git a/zul/src/main/resources/web/js/zul/sel/Treecol.ts b/zul/src/main/resources/web/js/zul/sel/Treecol.ts
index 2e4f5cc0a66..e6b22beca91 100644
--- a/zul/src/main/resources/web/js/zul/sel/Treecol.ts
+++ b/zul/src/main/resources/web/js/zul/sel/Treecol.ts
@@ -192,10 +192,12 @@ export class Treecol extends zul.mesh.SortWidget {
 	/** @internal */
 	override domContent_(): string {
 		var /*safe*/ s = super.domContent_(),
-			tree = this.getTree()!;
+			tree = this.getTree()!,
+			isPartial = tree.isIndeterminate() && !tree.$$selectAll && tree._selItems.length != 0;
 		if (this._hasCheckbox())
 			/*safe*/ s = '<span id="' + this.uuid + '-cm" class="' + this.$s('checkable')
-				+ (tree.$$selectAll ? ' ' + this.$s('checked') : '') + '"><i class="' + this.$s('icon') + ' z-icon-check"></i></span>'
+				+ (tree.$$selectAll ? ' ' + this.$s('checked') : isPartial ? ' ' + this.$s('partial') : '')
+				+ '"><i class="' + this.$s('icon') + ' z-icon-' + (isPartial ? 'minus' : 'check') + '"></i></span>'
 				+ (s ? '&nbsp;' + /*safe*/ s : '');
 		return s;
 	}
diff --git a/zul/src/main/resources/web/js/zul/sel/Treeitem.ts b/zul/src/main/resources/web/js/zul/sel/Treeitem.ts
index 41da9c5d59b..375558e6e5c 100644
--- a/zul/src/main/resources/web/js/zul/sel/Treeitem.ts
+++ b/zul/src/main/resources/web/js/zul/sel/Treeitem.ts
@@ -100,6 +100,8 @@ export class Treeitem extends zul.sel.ItemWidget {
 	_open = true;
 	treerow?: zul.sel.Treerow | undefined;
 	treechildren?: zul.sel.Treechildren | undefined;
+	/** @internal */
+	_partial?: boolean;
 
 	/**
 	 * @returns whether this container is open.
@@ -540,4 +542,33 @@ export class Treeitem extends zul.sel.ItemWidget {
 				_addSelItemsDown(items, newwgt as zul.sel.Treeitem);
 			}
 	}
+
+	/**
+	 * @returns whether it is partial selected.
+	 * @defaultValue `false`.
+	 */
+	isPartial(): boolean {
+		return !!this._partial;
+	}
+
+	/** @internal */
+	_setPartialDirectly(partial: boolean): this {
+		if (this._partial != partial) {
+			this._partial = partial;
+			const n = this.$n(),
+				tr = this.treerow;
+
+			if (n && tr) {
+				if (partial) {
+					jq(n).addClass(this.$s('partial'));
+					jq('#' + tr.uuid + '-cm .z-treerow-icon').removeClass('z-icon-check').addClass('z-icon-minus');
+				} else {
+					jq(n).removeClass(this.$s('partial'));
+					jq('#' + tr.uuid + '-cm .z-treerow-icon').removeClass('z-icon-minus').addClass('z-icon-check');
+				}
+				this._updHeaderCM();
+			}
+		}
+		return this;
+	}
 }
\ No newline at end of file
diff --git a/zul/src/main/resources/web/js/zul/sel/Treerow.ts b/zul/src/main/resources/web/js/zul/sel/Treerow.ts
index d23fc701c58..9c03e06441e 100644
--- a/zul/src/main/resources/web/js/zul/sel/Treerow.ts
+++ b/zul/src/main/resources/web/js/zul/sel/Treerow.ts
@@ -54,8 +54,14 @@ export class Treerow extends zul.Widget<HTMLTableRowElement> {
 		if (p && (!no || !no.zclass)) {
 			if (p.isDisabled())
 				scls += (scls ? ' ' : '') + this.$s('disabled');
-			if (p.isSelected())
-				scls += (scls ? ' ' : '') + this.$s('selected');
+			if (p.isPartial()) {
+				scls += (scls ? ' ' : '') + this.$s('partial');
+				jq('#' + this.uuid + '-cm .z-treerow-icon').removeClass('z-icon-check').addClass('z-icon-minus');
+			} else {
+				if (p.isSelected())
+					scls += (scls ? ' ' : '') + this.$s('selected');
+				jq('#' + this.uuid + '-cm .z-treerow-icon').removeClass('z-icon-minus').addClass('z-icon-check');
+			}
 		}
 		return scls;
 	}
diff --git a/zul/src/main/resources/web/js/zul/sel/less/tree.less b/zul/src/main/resources/web/js/zul/sel/less/tree.less
index b239d54a974..2e139e32d43 100644
--- a/zul/src/main/resources/web/js/zul/sel/less/tree.less
+++ b/zul/src/main/resources/web/js/zul/sel/less/tree.less
@@ -159,6 +159,15 @@
 			display: block;
 		}
 	}
+	//partial
+	&-partial {
+		> .z-treecol-icon {
+			color: @checkedColor;
+			display: block;
+
+			&.z-icon-minus {} //for checkbox partial selected state, use font-awesome
+		}
+	}
 }
 //paging
 .z-tree-paging {
@@ -289,6 +298,16 @@
 			cursor: default !important;
 		}
 	}
+	//partial
+	&-partial {
+		> .z-treecell > .z-treecell-content
+		> .z-treerow-checkable .z-treerow-icon {
+			color: @checkedColor;
+			display: block;
+
+			&.z-icon-minus {} //for checkbox partial selected state, use font-awesome
+		}
+	}
 }
 // hidden col
 .z-treecell-hidden-col {