procedure CreateWnd; override;
virtual void __fastcall CreateWnd();
Creates the underlying Windows control that implements the extended combo box.
The CreateHandle method calls CreateWnd to perform the task of creating the underlying Windows control.
The Windows control for the combo box can be temporarily destroyed and recreated in order to set properties that require changing the window creation parameters. Thus, CreateWnd may be called several times during the lifetime of the TCustomComboBoxEx instance.