procedure BeginUpdate; virtual;
virtual void __fastcall BeginUpdate();
Signals the start of an update operation.
Call BeginUpdate before starting an operation that performs changes to TCollection. After completing all the changes, call EndUpdate to signal the end of the operation. Every call to BeginUpdate must be matched by a corresponding call to the EndUpdate method.
For example, the method is used to suspend screen repainting until changes to a component that involves TCollection are completed.