[ctw]

Which regular, simple UI toolkits do you recommend to a web developer who wants to learn desktop development? Do you also have a recommendation on which resources/approaches to use to learn those toolkits?

[wander_homer]

Obviously this depends on what you want to do. Most importantly: Which platforms do you want to target?

[CyberDildonics]

Juce (GPL unless you pay for a license) FLTK Nanogui (simplistic GUI for openGL)

[Aaargh20318]

Use whatever is the native toolkit for the OS you're targeting.