TreeViewItem.IsExpanded Property    
Definition
Important
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Gets or sets whether the nested items in a TreeViewItem are expanded or collapsed.
public:
 property bool IsExpanded { bool get(); void set(bool value); };
	public bool IsExpanded { get; set; }
	member this.IsExpanded : bool with get, set
	Public Property IsExpanded As Boolean
	Property Value
true if the nested items of a TreeViewItem are visible; otherwise, false. The default is false.
Examples
The following example shows how to set the IsExpanded property.
<TreeViewItem Header="Employee1"
              Name="Employee1Data" 
              IsExpanded="True" 
              Collapsed="OnCollapsed" 
              Expanded="OnExpanded">
  <TreeViewItem Header="Work Days" 
                Name="EmployeeWorkDays"
                IsSelected="True">
    <TreeViewItem Header="Tuesday" />
    <TreeViewItem Header="Friday"/>
  </TreeViewItem>
</TreeViewItem>
<TreeViewItem Header="Employee2" 
              Name="Employee2Data">
  <TreeViewItem Header="Work Days" 
                Name="emp2WorkDays" 
                Selected="GetSchedule"
                Unselected="SetSchedule">
    <TreeViewItem Header="Monday" />
    <TreeViewItem Header="Wednesday"/>
  </TreeViewItem>
</TreeViewItem>
Employee1Data.IsExpanded = true;
Employee1Data.IsExpanded = True
	Remarks
The appearance of the button that expands and collapses the TreeViewItem changes when the TreeViewItem is expanded or collapsed. When the IsExpanded property value changes from true to false, the Collapsed event occurs. Similarly, the Expanded event occurs when the IsExpanded property value changes from false to true.
Dependency Property Information
| Item | Value | 
|---|---|
| Identifier field | IsExpandedProperty | 
Metadata properties set to true | 
None |