Toolbar (text under icons) font size.
Is there any common way to change font size and font family of text placed under icons on toolbars in Qt apps?
Just take a look into how GTK toolbars can be done (via css theming) compared to Qt app (Luminance HDR).
Have you tried to modify the font size of QToolBar by "setting a style":http://qt-project.org/doc/qt-4.8/qwidget.html#styleSheet-prop ?
Have you tried setFont on the tool bar?
Also, Qt supports CSS-style theming as well. I bet it works on toolbars too!