BOOL CALLBACK MonitorEnumProc(HMONITOR hmon, HDC hdc,
                              LPRECT prc, LPARAM lParam)
{
   // compute the color depth of monitor "hmon"
   int colorDepth = GetDeviceCaps(hdc, BITSPIXEL) *
                    GetDeviceCaps(hdc, PLANES);
   return TRUE;
}