Mouse Events

Notes:

• The constants LEFT_BUTTON, RIGHT_BUTTON and MIDDLE_BUTTON can be used to see which mouse buttons are currently held down.
• The buttons parameter in the call-back function is a bit-field.
• Use on_control_mouse_down to intercept mouse button clicks.
• Use on_control_mouse_up to intercept mouse button releases.
• Use on_control_mouse_drag to handle moving the mouse with one or more buttons held down.
• Use on_control_mouse_move to handle moving the mouse with no buttons held down.