Base input event type for mouse events.
Stores general mouse events information.
https://docs.godotengine.org/en/3.2/tutorials/inputs/inputevent.html
The mouse button mask identifier, one of or a bitwise combination of the [enum ButtonList] button masks.
The global mouse position relative to the current [Viewport] when used in [method Control._gui_input], otherwise is at 0,0.
The local mouse position relative to the [Viewport]. If used in [method Control._gui_input], the position is relative to the current [Control] which is under the mouse.