List of Mouse Callback Flags
One or more of the following values describing the state of the Shift/Ctrl/Alt keys and mouse buttons:
MOUSE_SHIFT
Indicates the Shift key is pressed.
MOUSE_CTRL
Indicates the Ctrl key is pressed.
MOUSE_ALT
Indicates the Alt key is pressed.
MOUSE_LBUTTON
Indicates the Left button is down.
MOUSE_MBUTTON
Indicates the Middle button is down.
MOUSE_RBUTTON
Indicates the Right button is down.