Although the new version of VirtualBox (2.x) uses Qt4, it does not link against a system Qt, but rather against an own version, which results in not making use of the global Qt4 theme. The issue can be overcome if system libQtCore.so.4 and libQtGui.so.4 are linked in place of libVBoxQt{Core,Gui}.so.4 in the VirtualBox directory. Reproducible: Always Steps to Reproduce:
Binary packages tend to be a maintenance hassle. Let's see what the maintainers want to do about outside dependencies vs bundled libraries.
Not sure about this though from knowing some parts of Qt, I think this is not fully possible if one doesn't have the same major version (4.4, 4.3,...). Though feel free to test and report back, I bet Alessio will thank you for test reports :)
It works for me with Qt 4.4.1 (by symlinking the libraries). I did not notice any misbehaviour. Apparently, the shipped version is 4.3.3, though: # strings /opt/VirtualBox/libVBoxQtCore.so.4.backup | egrep ^qt qt_global_mutexpool qt_application_thread_id qt_signal_spy_callback_set qt_startup_hook qt_allTopLevelWidgets qt_removeObject qt_addObject qt_disable_lowpriority_timers qt_demopath=/home/vbox/Qt-4.3.3-stdc++6-amd64/demos qt_xmplpath=/home/vbox/Qt-4.3.3-stdc++6-amd64/examples qt_stngpath=/etc/xdg qt_trnspath=/home/vbox/Qt-4.3.3-stdc++6-amd64/translations qt_datapath=/home/vbox/Qt-4.3.3-stdc++6-amd64 qt_plugpath=/home/vbox/Qt-4.3.3-stdc++6-amd64/plugins qt_binspath=/home/vbox/Qt-4.3.3-stdc++6-amd64/bin qt_libspath=/home/vbox/Qt-4.3.3-stdc++6-amd64/lib qt_hdrspath=/home/vbox/Qt-4.3.3-stdc++6-amd64/include qt_docspath=/home/vbox/Qt-4.3.3-stdc++6-amd64/doc qt_prfxpath=/home/vbox/Qt-4.3.3-stdc++6-amd64 qt_lcnsprod=Desktop qt_lcnsuser=Dmitry Kuminov qt_plugin_instance qt_plugin_query_verification_data In any case, Trolltech people do not seem to be very fond of breaking ABIs, so symlinking may well be an option.
Emerged QGtkStyle, made links to system Qt libs - works well and looks nice =)
So as they somehow broke stuff with 4.5, I'm still not liking that idea ;) (Look at kde4 mess for references), let's close this as a local workaround.
Frankly speaking, this still works perfectly for me with virtualbox-bin-2.1.4 and qt-4.5. Could it be a USE-flag (e.g. USE=system-qt4) with a big 'UNSUPPORTED' banner in the description so that people like me do not have to manually recreate symlinks after each emerge of VirtualBox?
