Hide the caption bar

procedure TForm1.HideTitlebar;
var
Style: Longint;
begin
if BorderStyle = bsNone then Exit;
Style := GetWindowLong(Handle, GWL_STYLE);
if (Style and WS_CAPTION) = WS_CAPTION then
begin
case BorderStyle of
bsSingle,
bsSizeable: SetWindowLong(Handle, GWL_STYLE, Style and
(not (WS_CAPTION)) or WS_BORDER);
bsDialog: SetWindowLong(Handle, GWL_STYLE, Style and
(not (WS_CAPTION)) or DS_MODALFRAME or WS_DLGFRAME);
end;
Height := Height - GetSystemMetrics(SM_CYCAPTION);
Refresh;
end;
end;


procedure TForm1.ShowTitlebar;
var
Style: Longint;
begin
if BorderStyle = bsNone then Exit;
Style := GetWindowLong(Handle, GWL_STYLE);
if (Style and WS_CAPTION) <> WS_CAPTION then
begin
case BorderStyle of
bsSingle,
bsSizeable: SetWindowLong(Handle, GWL_STYLE, Style or WS_CAPTION or
WS_BORDER);
bsDialog: SetWindowLong(Handle, GWL_STYLE,
Style or WS_CAPTION or DS_MODALFRAME or WS_DLGFRAME);
end;
Height := Height + GetSystemMetrics(SM_CYCAPTION);
Refresh;
end;
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
HideTitlebar;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
ShowTitlebar;
end;