I had the same problem and I decided on start building a few Qt apps for command line tools I had made. This worked quite well for me because it wasn't too complex or large, you tend to write in a 'modern' style (although the downside here is I guess that qt is also somewhat idiosyncratic) and you get a build tools so you don't need to worry much about that.
I forgot to mention that I did work on Both QT 3.x in the last decade. I liked it because I was working on VB at that time and was dying to find something similar for Linux(Was exploring RH those days). It did not help me to improve C++ though.
