Получилось!!!
В HostCFrames.HandleMouse нужно исправить последний цикл:
## Код:
```
REPEAT
    res := USER32.GetMessageA(msg, 0, 0, 0);
    IF (msg.message >= USER32.WMMouseMove) & (msg.message <= USER32.WMMButtonDblClk) THEN
      b := msg.wParam
    END;
    (**** BEGIN ****)
    IF msg.message = USER32.WMRButtonUp THEN
      res := USER32.ClientToScreen(wnd, pt);
      res := USER32.SendMessageA(wnd, 007BH, b, pt.x + pt.y * 65536) (* WMContextMenu *)
    END;
    (**** END ****)
    res := USER32.TranslateMessage(msg);
    res := USER32.DispatchMessageA(msg)
  UNTIL b MOD 4 = 0;
```
