For now I would vote for:

#define TOOL_BUTTON_SIZE 28 #define AUX_BUTTON_SIZE 22

but I think we need to try to add more stuff to the secondary toolbar to see how it will look.

Well, as it is the toolbar size forces the window to a fairly large minimum height. I'm a little uncomfortable forcing a much larger minimum size.

We have a lot of room to grow :) Currently the default window is very small - 400x400 if without the toolbar strut. BTW maybe we should increase this a bit, say to 640x480. But ultimately the size and maximized state of the document window should be remembered from previous session.

Do you think it would be okay to permit the button bar to be cut off if the window is resized smaller?

I think the main toolbar should not be cut (and it's not likely to be cut anyway), but the secondary toolbar must be permitted to be cut off if the window is small.

Well, perhaps I should use the GTK detachable toolbar widget there, though the plain GTK one is kind of weak. :/

What is wrong with it? Is there an alternative? Maybe in Gtkmm? It would be nice to have this done without coding it from scratch :)