private void updateTargetWindow(XMotionEvent xmotion) {
    assert XToolkit.isAWTLockHeldByCurrentThread();

    int x = xmotion.get_x_root();
    int y = xmotion.get_y_root();
    long time = xmotion.get_time();
    long subwindow = xmotion.get_subwindow();

    /*
     * If this event had occurred before the pointer was grabbed,
     * query the server for the current root subwindow.
     */
    if (xmotion.get_window() != xmotion.get_root()) {
      XlibWrapper.XQueryPointer(
          XToolkit.getDisplay(),
          xmotion.get_root(),
          XlibWrapper.larg1, // root
          XlibWrapper.larg2, // subwindow
          XlibWrapper.larg3, // x_root
          XlibWrapper.larg4, // y_root
          XlibWrapper.larg5, // x
          XlibWrapper.larg6, // y
          XlibWrapper.larg7); // modifiers
      subwindow = Native.getLong(XlibWrapper.larg2);
    }

    if (targetRootSubwindow != subwindow) {
      if (dragProtocol != null) {
        dragProtocol.sendLeaveMessage(time);

        /*
         * Neither Motif DnD nor XDnD provide a mean for the target
         * to notify the source that the pointer exits the drop site
         * that occupies the whole top level.
         * We detect this situation and post dragExit.
         */
        if (targetAction != DnDConstants.ACTION_NONE) {
          dragExit(x, y);
        }
      }

      /* Update the global state. */
      doUpdateTargetWindow(subwindow, time);

      if (dragProtocol != null) {
        dragProtocol.sendEnterMessage(sourceFormats, sourceAction, sourceActions, time);
      }
    }
  }
  /**
   * The caller must own awtLock.
   *
   * @returns true if the even was processed and shouldn't be passed along.
   */
  private boolean doProcessEvent(XEvent ev) {
    assert XToolkit.isAWTLockHeldByCurrentThread();

    if (processProxyModeEvent(ev)) {
      return true;
    }

    if (!dndInProgress) {
      return false;
    }

    switch (ev.get_type()) {
      case XConstants.ClientMessage:
        {
          XClientMessageEvent xclient = ev.get_xclient();
          return processClientMessage(xclient);
        }
      case XConstants.DestroyNotify:
        {
          XDestroyWindowEvent xde = ev.get_xdestroywindow();

          /* Target crashed during drop processing - cleanup. */
          if (!dragInProgress
              && dragProtocol != null
              && xde.get_window() == dragProtocol.getTargetWindow()) {
            cleanup(XConstants.CurrentTime);
            return true;
          }
          /* Pass along */
          return false;
        }
    }

    if (!dragInProgress) {
      return false;
    }

    /* Process drag-only messages. */
    switch (ev.get_type()) {
      case XConstants.KeyRelease:
      case XConstants.KeyPress:
        {
          XKeyEvent xkey = ev.get_xkey();
          long keysym = XlibWrapper.XKeycodeToKeysym(XToolkit.getDisplay(), xkey.get_keycode(), 0);
          switch ((int) keysym) {
            case (int) XKeySymConstants.XK_Escape:
              {
                if (ev.get_type() == (int) XConstants.KeyRelease) {
                  cleanup(xkey.get_time());
                }
                break;
              }
            case (int) XKeySymConstants.XK_Control_R:
            case (int) XKeySymConstants.XK_Control_L:
            case (int) XKeySymConstants.XK_Shift_R:
            case (int) XKeySymConstants.XK_Shift_L:
              {
                XlibWrapper.XQueryPointer(
                    XToolkit.getDisplay(),
                    xkey.get_root(),
                    XlibWrapper.larg1, // root
                    XlibWrapper.larg2, // subwindow
                    XlibWrapper.larg3, // x_root
                    XlibWrapper.larg4, // y_root
                    XlibWrapper.larg5, // x
                    XlibWrapper.larg6, // y
                    XlibWrapper.larg7); // modifiers
                XMotionEvent xmotion = new XMotionEvent();
                try {
                  xmotion.set_type(XConstants.MotionNotify);
                  xmotion.set_serial(xkey.get_serial());
                  xmotion.set_send_event(xkey.get_send_event());
                  xmotion.set_display(xkey.get_display());
                  xmotion.set_window(xkey.get_window());
                  xmotion.set_root(xkey.get_root());
                  xmotion.set_subwindow(xkey.get_subwindow());
                  xmotion.set_time(xkey.get_time());
                  xmotion.set_x(xkey.get_x());
                  xmotion.set_y(xkey.get_y());
                  xmotion.set_x_root(xkey.get_x_root());
                  xmotion.set_y_root(xkey.get_y_root());
                  xmotion.set_state((int) Native.getLong(XlibWrapper.larg7));
                  // we do not use this field, so it's unset for now
                  // xmotion.set_is_hint(???);
                  xmotion.set_same_screen(xkey.get_same_screen());

                  // It's safe to use key event as motion event since we use only their common
                  // fields.
                  processMouseMove(xmotion);
                } finally {
                  xmotion.dispose();
                }
                break;
              }
          }
          return true;
        }
      case XConstants.ButtonPress:
        return true;
      case XConstants.MotionNotify:
        processMouseMove(ev.get_xmotion());
        return true;
      case XConstants.ButtonRelease:
        {
          XButtonEvent xbutton = ev.get_xbutton();
          /*
           * Ignore the buttons above 20 due to the bit limit for
           * InputEvent.BUTTON_DOWN_MASK.
           * One more bit is reserved for FIRST_HIGH_BIT.
           */
          if (xbutton.get_button() > SunToolkit.MAX_BUTTONS_SUPPORTED) {
            return true;
          }

          /*
           * On some X servers it could happen that ButtonRelease coordinates
           * differ from the latest MotionNotify coordinates, so we need to
           * process it as a mouse motion.
           */
          XMotionEvent xmotion = new XMotionEvent();
          try {
            xmotion.set_type(XConstants.MotionNotify);
            xmotion.set_serial(xbutton.get_serial());
            xmotion.set_send_event(xbutton.get_send_event());
            xmotion.set_display(xbutton.get_display());
            xmotion.set_window(xbutton.get_window());
            xmotion.set_root(xbutton.get_root());
            xmotion.set_subwindow(xbutton.get_subwindow());
            xmotion.set_time(xbutton.get_time());
            xmotion.set_x(xbutton.get_x());
            xmotion.set_y(xbutton.get_y());
            xmotion.set_x_root(xbutton.get_x_root());
            xmotion.set_y_root(xbutton.get_y_root());
            xmotion.set_state(xbutton.get_state());
            // we do not use this field, so it's unset for now
            // xmotion.set_is_hint(???);
            xmotion.set_same_screen(xbutton.get_same_screen());

            // It's safe to use key event as motion event since we use only their common fields.
            processMouseMove(xmotion);
          } finally {
            xmotion.dispose();
          }
          if (xbutton.get_button() == XConstants.buttons[0]
              || xbutton.get_button() == XConstants.buttons[1]) {
            // drag is initiated with Button1 or Button2 pressed and
            // ended on release of either of these buttons (as the same
            // behavior was with our old Motif DnD-based implementation)
            removeDnDGrab(xbutton.get_time());
            dragInProgress = false;
            if (dragProtocol != null && targetAction != DnDConstants.ACTION_NONE) {
              /*
               * ACTION_NONE indicates that either the drop target rejects the
               * drop or it haven't responded yet. The latter could happen in
               * case of fast drag, slow target-server connection or slow
               * drag notifications processing on the target side.
               */
              processDrop(xbutton);
            } else {
              cleanup(xbutton.get_time());
            }
          }
          return true;
        }
    }

    return false;
  }