There is a group of consistency freaks out there (like myself) who are not very fond of mixing Gtk+ with Qt applications. The reasons for this are not just graphical, but also behavioural; Gtk+ applications behave differently than Qt applications (menus are different, layout is different, etc.). Trolltech obviously can’t tackle the behavioural side of this issue, but they can tackle the graphical one. This is exactly where QGtkStyle comes into play.QCleanlooks, combined with icon themes, standard shortcuts, and dialog buttons, already offer Qt integration into a Gtk+ environment, but this is not an ideal solution. From Qt’s point of view, a better solution would be to provide a solution for Gtk+ similar to what it offers on Mac OS X and Windows: using the Gtk+ theme engine directly. Cue QGtkStyle.
QGtkStyle does exactly this, and in addition extends and surpasses QCleanlooks in a lot of other areas as well. All group boxes are now flat style to blend better with GNOME dialogs. Icon theme support has improved, scrollbar buttons are disabled at edges and item view branches now support hover.
The style is available as a plugin to Qt 4.4 from the Trolltech Labs website – it is obviously not yet of release quality. It is also made clear that this style cannot be used concurrently with the gtk-qt-engine.