Occurs when the user presses a mouse button with the mouse pointer over a gutter.
property OnGutterClick: TGutterClickEvent;
Use the OnGutterClick event handler to implement any special processing that should occur as a result of pressing a mouse button.
The OnGutterClick 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. XY is the mouse coordinates in the client area of the Sender.