typedef void __fastcall (__closure *TTBCustomDrawBtnEvent)(TToolBar* Sender, TToolButton* Button, TCustomDrawState State, bool &DefaultDraw);
Sender is the toolbar that contains the button.
Button is the button that needs to be painted. Use its properties to determine what to paint and where the button sits on the toolbar's canvas.
State provides information that you may want to visually represent when painting the button.
DefaultDraw as True if the button should be painted using the normal process after the event handler exits. Set
DefaultDraw to False if the OnCustomDrawButton event handler has completely painted the tool button.