Nikos Chantziaras posted on Sat, 31 Mar 2012 12:16:06 +0300 as excerpted:
In case you missed it, you should install the Gtk port of Oxygen:
x11-themes/oxygen-gtk (and x11-themes/oxygen-gtk3 in case you need Gtk 3
later.) This isn't a "fake" theme btw. It's a real Gtk engine and
pretty much the official Gtk port of KDE's Oxygen style.
Thanks! I had seen the package mentioned, but FWIW I wasn't clear on
what oxygen bits it ported, etc. Your clarification that it's oxygen
widgets helps quite a bit there. (I run oxygen widget-styles but not
window trim or plasma-themes, so being unclear about what it did, plus
the below, I just figured it wasn't worth trying.)
Also, IIRC there were issues with it and for example qt-4.8, according to
the gentoo/qt and/or gentoo/kde project meeting reports, which I follow
when they're posted to the gentoo/desktop list. IIRC they triggered
segfaults in gtk-based apps for a bit, so I've been a bit cautious about
trying it. But I think that's fixed now and hopefully there won't be
similar issues in the future, so I might try it.