[dbl9]

GTK3 itself has various regressions and is slower than GTK2 despite the architectural refactoring lending itself to a snappier experience.

https://bugzilla.gnome.org/show_bug.cgi?id=771708

Firefox GTK3 has regressions too, for instance the bookmark manager not remembering where you were last which works with Firefox ESR (GTK2).

https://bugzilla.mozilla.org/show_bug.cgi?id=1267863

Also GTK3's file dialog is subjectively a huge regression, but others may prefer it, just like Apple's finder changed over time. I still haven't figured out how dconf and gconf work with GTK3, not using GNOME3 as a desktop.

There are more issues with GTK3 but these are the most visible for those of us who don't use GTK3 regularly as part of GNOME3 and have been forced to use it via Firefox. The way I read the GTK3 bugreport it seems like the devs don't test GTK3 outside GNOME3 and hence do not consider it a priority. That one dev has been stressing that a compositor is needed and multiple answers by the reporter that they're using a compositor seem to be missed during reading on the other side. It's a weird exchange. I'm with the reporter. If GTK3 is not supposed to or not tested outside GNOME3, then this should be communicated so that everyone can make an informed decision to use something else or revive the Firefox Qt toolkit code.

[jhoechtl]

Serious comment:why bother with gtk anyhow and move to Qt?

[dbl9]

I love GTK2, but I can do without GTK3, seeing we're at 3.22 and it's still not as stable or regression free as GTK2.

I'd be the first to build and use a Firefox where the Qt port was updated and made to work but GTK is the GUI toolkit used by Firefox outside Android, macOS and Windows. That said, GTK2 was and still is very good at what it does. It just works but doesn't support Wayland.

I cannot move to Wayland anyway until xterm or rxvt-unicode are ported since XWayland integration is still imperfect. Like they wrote in the bug report, while GTK2 doesn't have a Wayland backend, GTK3's backend isn't really production quality either with dialogs sometimes opting to zoom out rather than scale out or general stability issues. If you try to start Firefox under Wayland by telling GDK to use Wayland, it just crashes on startup.