When a label presenter inside data presenter is clicked and dragged, it's IsDragSource will be set to true. Note that this is not the label presenter that's embedded inside drag indicator. To check if a label presenter is embedded inside the drag indicator window, use its property.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, 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