Coolbar & Toolbar

I have a toolbar inside a coolbar, but when the user resizes the windows to an smaller size, some buttons dissapear... what I'm trying to do is the same effect that Windows has, you know, when this happens to any application it shows a small button with 2 right arrows (">>") that allows the user to see the missed buttons in a menu. Is there any way to do that with or without the API ????

The other question that I have is if there's an API call that turns a toolbar transparent... so that when the users sees the form, he will see the background image of the coolbar, instead of a gray boring color.