With virtualbox and VLC both requiring QT libraries on my otherwise GTK based desktop (XFCE with some Gnome components) the KDE look doesn’t mach the rest of my desktop’s look and feel. To solv this probelm (in Fedora 12, might work on other distros) I ran gtconfig-qt4 in terminal as a normal user. The configuration GUI and under Select GUI Style I choose GTK+ and close the configuration GUI. Now the QT applications look like my GTK applications.