Yeah, the question was tongue in cheek. Which one do we use then?

I guess the best option is GTK+ because of the number of users?

There are themes that mimic GTK apps on Qt and vice versa and they look like crap.

But in my opinion Qt apps also look like crap on Windows and Mac. They look somewhat like a native app, but everything is off.

For example, if you have a Qt app on Windows and you click a menu separator, the menu closes, <s>like it would do on Mac</s>. On Windows, clicking a menu separator should do nothing, the menu should remain open. There are dozens of little annoyances like that. Not to mention padding/spacing of elements, etc.

Of course, Qt is very useful. I've worked with it (using QWidgets) and I've liked it a lot, despite of its drawbacks. But it's certainly not native. It merely emulates the target interface.

I'm reading this on a Mac; I clicked on the File menu in Safari, then clicked a menu separator, and the menu remained open.

This does not, of course, invalidate your main point in any way. (I also currently have p4v open on another display, and, well.)