true if the LayoutAnchorable or LayoutDocument will appear over all other windows when floating, otherwise false. By default, false.
Remarks
If more than one pane or group has this property set to true, the last one created will be on top of all others.
Requirements
Target Platforms: Windows 11, Windows 10, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2