int pascal ToggleEGA(void)

  This function toggles the display between 25 and 43/50 line modes if
you have an EGA or VGA card.  If the mode change is successful, then
MEWEL will send the WM_DEVMODECHANGE message to all top level windows
with the string "SCREEN" in the lParam argument. This will give your
application a chance to make any changes to reflect the new video
mode.

Parameters
  None.

Returns
  None.