[raverbashing]

WxWidgets worked fine and it was very easy to integrate on small C++ projects when I tried. If you just need some basic windows it's the way to go.

Qt is good but it requires you to go fully into the Qt ecosystem (build tools, etc) not sure about QML though.

[bsenftner]

I second wxWidgets. It can produce small executables, like 50K, that sport a complete modern UI. Just look for the AUX addition, that the more modern and customizable version.