SelectionStart returns the starting location of the current text selection. If nothing is selected, it returns the location of the caret. You can set this property to change the selected text. Note that setting this property does not modify the contents of the control.
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