We have JavaFX and Qt, and they're both better than ever, but they don't see much use. With JavaFX you can build and distribute a portable .jar file, and I think it can be used with JNLP/Java Web Start for distribution if you prefer that approach. With Qt, you're likely to be delivering self-contained native application packages in the target platform's native form.
(JavaFX has been carved out of the core JVM, which is annoying, but if the target machine has a JVM installed that bundles JavaFX, you're all set.)
I'm not sure you can say that Qt doesn't see much use, when there are hundreds, probably thousands, of well-known commercial apps using it, and it's in millions upon millions of embedded systems. And obviously KDE as well.
It's just it's largely invisible. It works, it does exactly the job it's meant to do, and it does it well.
(JavaFX has been carved out of the core JVM, which is annoying, but if the target machine has a JVM installed that bundles JavaFX, you're all set.)