Configure easily themes of GTK+ applications, QT4 applications ...

It's not always immediate to configure Themes of Desktop Environment, GTK+ applications and Qt4 applications separately.

For Desktop environment, there is usually embedded tools.

For GTK+ applications, we can use the gtk-chtheme tool.
Under RedHat-like GNU/Linux, it can be installed with the package of the same name:
yum install gtk-chtheme
Each user wanted to configure his GTK+ applications theme can then use this tool.

For Qt4 applications, we can use the qt-config tool.
Under RedHat-like GNU/Linux, it can be installed like that:

yum install qtconfig-qt4

Each user wanted to configure his Qt4 applications theme can then use this tool.

Lots of themes can be found on OpenDesktop.