Occurs when the user releases a mouse button that was pressed with the mouse pointer over a component.
Use an OnMouseUp event handler to implement special processing when the user releases a mouse button.
The OnMouseUp event handler can respond to left, right, or center mouse button presses and shift key plus mouse-button combinations. Shift keys are the Shift, Ctrl, and Alt keys. X and Y are the pixel coordinates of the mouse pointer in the client area of the Sender.