If you only allow the title bar, how will the user be able to do anything, like get back to the previous form or the main form??? I'm just curious.
What you can do is set up a dummy form, without controls, with a height of 0 and call this form from whatever form you want to make as small as possible. You just need a way to navigate between forms. By this I mean if the second (or any other form for that matter) is so small that the only thing visible is the title bar, how does the user do anything???