On my system, ardour exhibits the following behaviour (tested with current SVN heads for 2.0-ongoing and 3.0): when adding tracks, the editor window minimum height expands until it reaches full screen height. Only then will the vertical scroll bar become active.
Most people probably run ardour fullscreen anyway and therefore won’t care about this, but I just switched to a dual-screen L-shaped Xinerama setup (which I need for other reasons), and in that context, this is obviously deadly.
Am I maybe overlooking a configuration option somewhere?
I might be confused about how the layout system you’re using works, but easiest would probably be a configuration switch, “do not change top-level window sizes” (or rather, “decouple main window size from track canvas size” or similar). That would leave the problem entirely to the user.
More in keeping with the spirit of the current behaviour would be to expand the window vertically unless doing so would unmap parts of the window. This is likely to be a pain to code and test, though.
One useful addition (if it doesn’t exist yet for the cases when maximum height has been reached) would be to add scrolling to ensure that at least one pre-existing and one newly added track are visible after the add operation.
I’m willing to implement either of these; it would likely take a while, though, because my Gtk(mm) knowledge… isn’t (I went from Xaw/Xlib to Qt and never looked elsewhere).