How to make toolbars on the window title

how do I do things like this or like,

the buttons are draw in the window titile bar.

It'd require some tricky hackery to overlay NSViews.. It's non trivial but also something that's commonly done so we'll probably want to support this, just can't give you a promise about when that'll be. (Actually, it's something we'll probably want to use ourselves here at ROLI so that'll make it happen faster)