I'm being a bit off topic, but one problem I have with having both Gtk2 and Gtk3 apps is that there have been settings and theme discrepancies. For example, I use Linux Mint MATE, and there have been some problems with bookmarks being in sync between the file open dialog in Gtk2 apps vs Gtk3 apps. Plus, if I don't use a theme that is available in both versions of Gtk, then I end up with foreign looking apps in my environment, almost like I'm port forwarding X and getting things theme-less. Even geany hasn't been flawless in this Gnome Civil War, with the default external file browser being nautilus, where my system uses the nearly identical caja, although I changed the setting in geany of course.