How can I hide the form caption bar??

First, override the "CreateParams" method of your Form, by declaring this in either your Form's protected or public section:

procedure CreateParams(var Params: TCreateParams); override;

Then, in the actual CreateParams() method, specify something like this:

procedure TForm1.Createparams(var Params: TCreateParams);

begin

inherited CreateParams(Params);

with Params do

Style := (Style or WS_POPUP) and (not WS_DLGFRAME);

end;

Hopefully, you'll provide some UI mechanism for moving and closing the window.