QFileSystemModel Root and Thumbnail

Hi all,
I have finished my content browser but I still have one last problem actually who is the root item.
I already asked here but I didn't found any way to achieve that (http://www.qtcentre.org/threads/5936...stemModel-root).
You can see the final result here : http://uppix.com/f-ContentBrowser1653acbf140016dbc5.png.
The problem as you can see is I only can go back to root using history or the path on the top.
There is surely one way to have root item, Do I have to rewrite my how model and stop to use QFileSystemModel ?
My second question is about thumbnail because the goal is to store thumbnail in my asset files.
Is it better to render them using the model or QFileIconProvider ? Maybe that end to the same ?
Thanks for the help