Check out the software section to get the source for an IMGUI test that I did a while back. I wanted to see if some classic Retained Mode gui concepts were at all possible in Immediate Mode. Looks like they were!
I'm currently preparing material for a course on multiplayer and network programming which I will be holding during August at GameMaker in Arvika. I'm looking forward to what I think will be a great course!
I will be basing the course on lots of my own experience at Massive Entertainment, as well as my more recent thoughts on MVCE. As a reference, I will be showing off the current state of Bangu Bangu Sosaru, a little capture-the-flag multiplayer game I have been developing.