/** Activate automatic grab on first ButtonPress, deactivate on full mouse release */
 public void handleButtonPressRelease(XEvent xev) {
   XButtonEvent xbe = xev.get_xbutton();
   final int buttonState =
       xbe.get_state() & (Button1Mask | Button2Mask | Button3Mask | Button4Mask | Button5Mask);
   switch (xev.get_type()) {
     case ButtonPress:
       if (buttonState == 0) {
         XAwtState.setAutoGrabWindow(this);
       }
       break;
     case ButtonRelease:
       if (isFullRelease(buttonState, xbe.get_button())) {
         XAwtState.setAutoGrabWindow(null);
       }
       break;
   }
 }