procedure RemoveControl(Control: TControl); virtual;
virtual void __fastcall RemoveControl(TControl* Control);
Handles the undocking of a control from the associated DockSite.
The windowed control that uses the dock tree calls RemoveControl when one of its docked controls is undocked.
Control is the control that was just undocked.
RemoveControl adjusts the dock tree's internal structures to indicate that the control is no longer docked, changes the control's DockOrientation property to doNoOrient, and calls DockSite's Invalidate method so that the region is repainted.