virtual void __fastcall BeginUpdate(void) = 0 ;
Responds when the docked controls are about to change.
BeginUpdate is called before controls are docked or undocked.
Once all docking or undocking is complete, the EndUpdate method is called so that the dock manager can make any final adjustments to reflect the final set of docked controls. Every call to BeginUpdate should be paired with a call to EndUpdate. BeginUpdate/EndUpdate pairs can be nested.