procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Integer); dynamic;
DYNAMIC void __fastcall MouseDown(System::Uitypes::TMouseButton Button, System::Classes::TShiftState Shift, int X, int Y);
OnMouseDown event dispatcher.
Override the protected MouseDown method to provide other responses in addition to calling the OnMouseDown event handler when the user presses the mouse button down while the cursor's hotspot is over the control.
The Button parameter determines which mouse button the user pressed. Shift indicates which shift keys (Shift, Ctrl, or Alt) were down when the user pressed the mouse button. X and Y are the pixel coordinates of the mouse pointer within the client area of the control.
A control calls MouseDown in response to any of the Windows mouse-down messages (WM_LBUTTONDOWN, WM_MBUTTONDOWN, WM_RBUTTONDOWN), decoding the message parameters into the shift-key state and position, which it passes in the Shift, X, and Y parameters, respectively. The value of the Button parameter indicates which mouse button was pressed down: left, right, or middle.