TToolBar is mainly designed for TToolButtons, placing there anything else is a hack. It may work but who knows, especially if you want TEdit together with toolbuttons.
I recommend this: use TCoolBar and Bands. One band for TEdit, other band for TToolBar with toolbuttons.
EDIT: I have good experience in Qt, GTk2 and WIne. I didn't notice that this is Cocoa thread. Cocoa seems to be under develepment, my advice is more "general".