Apparently this issue is still around. I just compiled with --enable-gtk3 on a Fedora 18 (x86_64) box. It seems fine, until you are using multiple tabs and you close the forelast tab. That will definitely give you an extremely tiny (totally unusable) lxterminal box.
When compiled with gtk3 on, I can barely see the text in the tabs of pcmanfm. I have done a little investigation and believe the gtk_label_set_ellipsize is the culprit. When disabling that one in tab-page.c then I can finally see the complete tab label.