@vanschelven, thanks for your PR! By analyzing the history of the files in this pull request, we identified @vcunat, @Fuuzetsu and @dezgeg to be potential reviewers.

I can't really weight in on the "by design or not" from the perspective of NixOs; other than the fact that the fact that most packages are stuck on a pre-gnome3 version might as well be explained by laziness (not to be understood as a language feature but rather a feature of humanity) as by being a design decision proper.

I did do a bit of research on whether there are any Xfce-given reasons to hold back to the GTK+2 versions, but I can't really find any such indication on their site. As a matter of fact I couldn't find any support schedules on the Xfce site, which leads me to understand their policy as "just push forward and let the distributions deal with the rest" - but I might be wrong.

The first version of Xfce that contained GTK+3 components was Xfce 4.12, released on February 28, 2015. Also there's this discussion on moving forward to Xfce 4.14, which talks of a full transition to GTK+3.

And then there's "what is everyone else doing"; at least Ubuntu, Fedora & Arch are pushing forward to the new Xfce libraries. Millions of users can't be wrong 😛

gtk3 in xfce hasn't been declared stable yet upstream AFAIK.

Once I have submitted a PR (#16658) to update libxfce4ui_gtk3 to version 4.13.0, which is considered unstable. So I have closed it.

@volth said

I am not against the progress, but I think it might have sense to do the upgrade of all xfce components at once (release of 4.14 is a good timepoint for that) to avoid possible inter-component issues as they migrate to gtk3 one by one.

I agree, so I'll close this PR for now.

For future reference, I've asked on the xfce dev mailing list what the status of the various projects is. The answer is here:

https://mail.xfce.org/pipermail/xfce4-dev/2017-June/031966.html

The most important bits are:

Xfce 4.12 is stable, Xfce 4.14 will be considered stable when it's released.

If you look at https://mail.xfce.org/pipermail/xfce-announce/ archives, you'll see that lots of 4.12 components got bugfix/point releases since 4.12.0. Once 4.14 is released, bugfixes should concentrate on that 4.14 branch, there's not enough manpower to maintain two branches with totally different base components..

As for stability, some distros started shipping parts of Xfce using already-migrated-to-gtk3 components, most of the developers are running Gtk3 versions of components (4.13.something, considered 'development releases'), bugs are being squashed out, and (to me) it's usable daily. YMMV.

Well, if we knew 4.14 would be ready before our next stable release (September), I wouldn't be against migrating all Xfce to the gtk3 versions now (in advance), but I don't think they would give similar "guarantees".