Gets the leaf active control of the active form. If this is overridden in derived classes, it should call the base implementation first. If the base returns null, additional code should be used to find the active control of the active form. All toolbars managers used in an application should have the same implementation of this property or inconsistent behavior will occur.
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
