You can do this with the file_exclude_patterns global preference

Yeah, libgio is part of gtk, and hence part of gnome. You'd have to upgrade to a newer version of gnome, and I don't know if that's something you can do in ubuntu without moving to a new version of ubuntu or not - I'd guess not. If you did upgrade to a newer version of ubuntu, I'm not which version comes with libgio >= 2.26.

It will open up in an existing window if your version of Ubuntu is new enough. If you run it from the command line, it'll print a message to stderr if your version of GTK isn't recent enough for the single instance functionality.

After running, you'll be able to find the icon in ~/.Sublime Text 2/Packages/Defaut/Icon.png

I believe the usual behaviour is to make the window the minimum size such that no scrolling is required

Which debs are you referring to? Currently, Sublime Text 2 is distributed as tarballs only.

This was added a couple of versions ago: http://www.sublimetext.com/docs/2/osx_command_line.html

Do you mean that when you press escape, you're not being returned to where you were?