typedef void __fastcall (__closure *TMouseWheelEvent)(System::TObject* Sender, System::Classes::TShiftState Shift, int WheelDelta, bool &Handled);
Procedural type that is used for all OnMouseWheel event types.
A TMouseWheelEvent event handler must be called with the following parameters:
Sender--a pointer to the object that called this function.
Shift--indicates which shift keys--SHIFT, CTRL, ALT, and CMD (only for Mac)--were down when the user pressed the mouse button.
WheelDelta--indicates the distance the wheel was rotated.
Handled--indicates whether the scroll bar was already moved.