button-changed? in mouse-event%

Returns #t if this was a mouse button press or release event, #f otherwise. See also button-up? and button-down?.

• (send a-mouse-event button-changed? button) -> boolean
     button = 'any : symbol in '(left middle right any)

  If button is not 'any, then #t is only returned if it is a release event for a specific button.