styles WS_VISIBLE and CCS_TOP.
- Implement messages WM_NCHITTEST, WM_STYLECHANGED, RB_MOVEBAND,
  RB_MINIMIZEBAND.
- Improve preformance by removing calls to GetWindowLong for GWL_STYLE
  (by saving state and handling WM_STYLECHANGED).
- Cleanup and remove dead and test code.