Prevent window from resizing

You should trap WM_GETMINMAXINFO message. In your form's class declaration put this:

  procedure WMGetMinMaxInfo(var Msg: TWMGetMinMaxInfo);
    message WM_GETMINMAXINFO;

and in the implementation section:


procedure TYourForm.WMGetMinMaxInfo(var Msg: TWMGetMinMaxInfo);
begin
  inherited;
  with Msg.MinMaxInfo^ do
  begin
    ptMinTrackSize.Y:=200;
    ptMaxTrackSize.Y:=400;
  end;
end;