I learned most of this stuff from this awesome series of articles by Larry Price. Give it a read, it’s worth it. Why D-Bus daemons are quite useful tools. What would you need them for?
I am a quite avid reddit user. Like it or not, reddit is a very central place where communities for stuff that I care about tend to aggregate. For the longest time, I have felt the need for a reddit app on my Linux desktop, and I waited and kept waiting for one that would finally allow me to break free of using the web version.
The back and forward buttons on your mouse are incredibly useful, at least for me. I use them all the time! I couldn’t find a proper way to map it on my app until I asked on the GTK Matrix chatroom, there baedert sent me a couple of links to how he did it in his app corebird.
One of the most common things you might wanna do with images, that is making them automatically resize to adapt to the available space they have, is not possible with Gtk.
Man pages are awesome. They genuinely are. In any *nix system you can just get documentation on your programs or even some programming things (namely a lot of C stuff, this was very useful in University) offline by just using a tiny simple command.