Adding the current session filename in the statusline
===

I recently added the [sessionman](http://www.vim.org/scripts/script.php?script_id=2010) plugin to my vim configuration and I like it so far.

I understand that vim sets `v:this_session` to the session filename when a session is being used and I'd like to add it to my statusline. Unfortunately, `v:this_session` contains the full file path and it is often way too long for it to fit in the statusline.

So my question is: how can I extract the filename without its full path from `v:this_session` and add it to my statusline ?

Thank you.
