EndUpdate is called after a series of changes to the docked controls is completed. It checks that every previous call to the BeginUpdate method has been matched with an EndUpdate call. If so, it performs any final adjustments to the docked controls, now that they are all in place. 

Each call to EndUpdate should be paired by a call to BeginUpdate, which is made before docking or undocking controls. BeginUpdate/EndUpdate pairs can be nested. 

BeginUpdate