I believe that it is a common habit to use a name of "<Application name> <Application type>" in an application's .desktop file. If that is the case, then Mousepad's name ought to be "Mousepad Text Editor". If not, please disregard this bugreport ;-)
That's wrong. The application name (Mousepad) and the application generic name (text editor) has different fields. It is up to the program that displays the .desktop file to choose how it wants to display this information. As far as I can see, the "Generic Name" field in mousepad.desktop is filled in correctly.
Hmm, while I can understand the reasoning, it still seems to be the (de facto?) standard to use e.g. "Thunar File Manager" as the Name, and "File Manager" as the GenericName. Besides, both the Xfce menu and Thunar do not display the GenericName (which would be odd, too, as most applications do it the way Thunar does it, which would become "Thunar File Manager File Manager").
I cannot see that putting the generic name after the real name is the de facto standard. In fact, in my XFCE menu, only a few does it. In my opinion, Thunar should be re-labelled instead.
Done in the correct way. Closing.