Add support for desktopFileName to NETWinInfo
Review Request #126028 - Created Nov. 11, 2015 and submitted
Implementation for the new hint _NET_WM_DESKTOP_FILE, see . Till it's fully standardized going with a KDE prefix, so it's _KDE_NET_WM_DESKTOP_FILE. Once it's specified the atom name can be exchanged.  https://mail.gnome.org/archives/wm-spec-list/2015-November/msg00000.html
tested with a modified kcmshell5 and a modified desktop file.