The lightweight LXDE desktop environment, for now developed in GTK2, will be rewritten by using the Qt tool-kit (not with GTK3, as it should be logic).
In collaboration with the RazorQt team, the developers use Qt4 to rebuild LXDE, but they intend to port it in Qt 5.1, when it will gain popularity among the Linux distros.
Besides the rewritten interface, the developers aim to create a new file manager, named PCManFM-Qt and other configuration tools. The new project is called LXDE-Qt. They decided to switch to Qt in order to make a lighter DE, a result that cannot be achieved by using GTK3.
The new LXDE will be available soon for testing on Arch Linux, via the AUR repo. Just install the lxpanel-qt and qt-lximage packages on an updated system.
$ pacman -Syu
$ pacman -S lxpanel-qt qt-lximage