The splitter is considered collapsed any time the target control's extent is at it's minimum size, as determined by the target control's MinimumSize property. Collapsing does not include the MinSize property on the Splitter control. This is to allow collapsing to 0 when MinSize is set.
The splitter can be collapsed by setting the Collapsed property, calling the Collapse method or by dragging the splitter to the minimum size.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, 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