Since www-client/opera snapshots come with both GTK+ and KDE4 UI modules, www-client/opera is always using the KDE4 one, even though: 1) I'm running XFCE, 2) I have no KDE4 (and thus no libkde* depends of liboperakde4.so), 3) (with 10.60*) opera has USE='gtk -kde'. Moreover, it seems like Opera is not even considering using GTK+ UI. If I remove liboperakde4.so, Opera starts in 'native X11' GUI anyway. To get the GTK+ UI, I have to rename 'liboperagtk.so' to 'liboperakde4.so'. I don't know what Opera uses to determine which UI to use but I guess it should at least try GTK+ if KDE4 libraries are unavailable. As a workaround, the ebuild could do the rename mentioned above when USE='gtk -kde'.
I can't help you there. Ask a the [URL] how to fix this and please report back.
Ok, I've got an additional knowledge: this can be set through opera:config 'File Selector -> Dialog Toolkit', where 1 seems to stand for KDE4, and 2 for GTK+. But I guess we aren't really able to control it in other way than creating a wrapper modifying user's operaprefs.ini. I'll try to ask on IRC too.
