code: func IsMouseButtonJustReleased(button ebiten.MouseButton) bool {
  	theInputState.m.RLock()
  	r := theInputState.mouseButtonDurations[button] == 0 &&
  		theInputState.prevMouseButtonDurations[button] > 0
  	theInputState.m.RUnlock()
  	return r
  }
docs: // IsMouseButtonJustReleased returns a boolean value indicating
  // whether the given mouse button is released just in the current frame.
  //
  // IsMouseButtonJustReleased is concurrent safe.