Dino File Manager (DFM) is a File manager written in Qt, which promises to be lightweight and functional. Although its development is still in a very early stage, it is already perfectly usable and needless to say, the integration with KDE o RazorQT it's excellent.
Dino it's fast, it has tabs and even its own integrated text editor. It can be completely controlled by keyboard shortcuts, with which we can create folders, create symbolic links, create custom actions, and work with our files.
It has a very simple view mode that allows you to display folders in the form of a tree. The tabs can be placed at the top or bottom and the only problem it has is that it consumes a few Mb more than Thunar y Nautilus with a single window / tab open.
The source code of the project can be obtained at the following link http://dfm.sourceforge.net/ and luckily for us, we can test it in most of the most popular distros since it is in their official repositories.