I faced that question over a decade ago, and after looking around at my options, I went with Qt. No regrets. Sure, it had its flaws, and sometimes the "not-quit

I faced that question over a decade ago, and after looking around at my options, I went with Qt. No regrets. Sure, it had its flaws, and sometimes the "not-quite-nativeness" shows through, but it worked pretty well and gave me support for all 3 major desktop systems. And although someone else has long since taken over maintenance of the application in question, it's still going strong (and still built with Qt).