completely incorrect message flow)
- update monthcal after date change in datetime
- choose different coordinates when DTS_SHOWNONE is not used
- embedded monthcal is now 200 pixels wide
- selecting a day in embedded monthcal updates the datetime and hides
  the monthcal
- changing months/years by clicking month name/year in title bar works
- embedded month calendar is correctly destroyed (it used to stick on
  the screen long after the datetime's container was closed)