Screwed up toolbars

I have 4 toolbars in my mainframe window. When I resize that window (making it smaller in width) all the toolbars are placed on top of each other on the left side, which is a normal feature. When I resize it again (making it wider), the toolbars stay on top of each other instead of docking besides each other on the top line. Does anyone know how to change that?

Thanks,

Anthony

[GameDeveloper]

Maybe it's supposed to happen?