How to collapse the context menu button of docked windows in WPF DockingManager?

 
<syncfusion:DockingManager x:Name="SyncDockingManager" IsContextMenuButtonVisible="False">
 
<ContentControl x:Name="SolutionExplorer" syncfusion:DockingManager.Header="Solution Explorer" />
 
<ContentControl x:Name="ToolBox" syncfusion:DockingManager.Header="Toolbox" />
 
<ContentControl x:Name="Properties" syncfusion:DockingManager.Header="Properties" />
 
<ContentControl x:Name="Properties1" syncfusion:DockingManager.Header="Output" />
 
<ContentControl x:Name="StartPage" syncfusion:DockingManager.Header="Start Page" />
 
</syncfusion:DockingManager>
 
 

dockingmanager.IsContextMenuButtonVisible = false;