Now on the recent menu appear icons representing the type of media in the list are displayed.
It works by setting the media type on open and storing in a string list in smplayer.ini, recents/types
I am not an experienced programmer with C++ nor with QT, the code is not so good & elegant but it worked for me.
The old entries already present in the recent menu get the 'unknown_type' icon. As far as I can tell there is no way to set the right icons for those unless each of those items get reopened: it would have been eccessive do it from within the functions modified.