This property represents the local CLR property of the AreGroupsFlattened attached property.
When set to true, child groups are all aligned with the left-most (or right-most if the flow direction is right to left) parent group.
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