That property has effect only if ImageFiles is used and the Width of control in set in %. It prevents breaking background image on separate parts when width of control becomes too large.
Requirements
Target Platforms: Windows 10, Windows 8.1, Windows 8, 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