GTK+ themes in Qt applications

Qt Desktop applications need a little help to use your desktop theme in GNOME.

Setup

The GTK+ style for Qt can be built by setting the gtkstyle USE flag for dev-qt/qtgui.

Set the gtkstyle USE flag. If there is a blocker, unset the qt4 flag in x11-libs/cairo:

File/etc/portage/package.use

dev-qt/qtgui gtkstyle
x11-libs/cairo -qt4

and rebuild the packages with their new USE flags:

root # emerge --ask --changed-use qt-gui cairo

You might need to reselect the preferred theme for Qt applications using qtconfig (from dev-qt/qt3support):

user $ qtconfig

or just delete the previous configuration files:

user $ rm -r ~/.config/Trolltech*

Select the Default theme to use your system settings or set it to use the GTK+ style explicitly by selecting GTK+ theme.

Individual applications might have their own configuration settings for their GUI, e.g. in VLC this is located in Tools → Preferences.

32bit applications on multilib systems are still unaware of the system's GTK+ theme, probably because app-emulation/emul-linux-x86-qtlibs is compiled without the gtkstyle USE flag enabled.

An alternative for users of GTK+2 and Qt4 is using the QtCurve cross-toolkit theme:

root # emerge --ask gtk-engines-qtcurve qtcurve-qt4

The downsides of this method are that it's not available for GTK+3 yet, and currently the only configuration GUI needs KDE4.