Gtk-3.0 applications - e.g., firefox - now look like crap under Xfce using most of the default themes. This is due to the fact that the x11-themes/gtk-xfce-engine is built without gtk-3.0 support. Support for gtk-3.0 can be enabled by adding a CONFIGURE_ARG="--enable-gtk3" to the Makefile and then by updating the plist to add all the extra gtk-3.0/gtk.css files that are installed.
Thanks for the suggestion.
I'll have a look and do some tests.
(In reply to Guido Falsi from comment #1)
No, it's bad idea. Gtk3 is not supported by the gtk-xfce-engine (it works fine for early version of Gtk < 3.8). There're lots of change since 3.18.
if you need a good Gtk3 theme, install gnome-theme-standard (and select Adwaita theme). It contains both Gtk2 and Gt3 themes (and it follows update of the GNOME team). You can also try the Greybird theme (there is an update on the BugZilla).
At the time there was a discussion about it . Moreover gtk-xfce-engine is now deprecated by upstream (not any more maintained).
Thanks for the pointer on needing x11-themes/gnome-themes-standard to get the Adwaita theme. I already had x11-themes/adwaita-icon-theme and therefore thought I had this theme, but apparently the latter is just the icon set and not the Gtk themes.
Even though the file share/themes/Adwaita/gtk-3.0/gtk.css is empty (save for a comment saying the file is not used), installing this port does seem to fix a lot of the ugliness I was seeing with firefox and other gtk3 apps.
So, if gtk-xfce-engine is being deprecated, I guess adding the Gtk3 port compilation option is moot.
Closing this bug.
Thanks to Olivier for providing the information and links.