[sime2009]

> GTK

GTK hasn't been well maintained or developed for ages and has always had poor docs. I wouldn't feel confident trying it on any platform which isn't its home (i.e. Linux).

> Qt

Qt is probably the best option in the list but it's language support is poor, only C++ and Python are practical. It is a big fully featured and mature library, but developing with QML is a poor experience compared to the tooling available on Chrome/Electron. Packaging and distributing Python and/or C++ Qt apps is a huge PITA too.

> WPF for Windows

not cross platform

> JavaFX

JavaFX looked interesting but just didn't seem to take off and develop a reasonable ecosystem around it. Certainly nothing that could rival the web ecosystem. I do love the language support that the JVM delivers. Regarding deployment size it isn't likely to be much better than Electron as most apps have to ship the whole JVM anyway. The stench of Oracle does taint it these days too.

> Tk

be serious

> LibUI

This isn't mature yet and it looks like another optimistic adventure in "write once, debug everywhere" like WxWidgets.

None of the options here can compete with Electron in terms of ecosystem or developer experience (often Chrome's dev tools). Nor are they built on open standards. Also JS is up there with the JVM and .Net platform in terms of languages which target and can run on it.