I don't think this is a good idea. As soon as the user changes the toolbar, this data becomes invalid. And it is no problem to get the width on the fly.
Session saved toolbar size is the real size. If a short toolbar occupies the whole line, its width is the whole line. Then, two short toolbars in different lines will have long widths saved in session, which then tells us to put them into two separate lines during restoration. If your approach always put two short toolbars in the same line, it is wrong. Bo
