In Nautilus I tried to rename a .desktop file, but Unity (or is it Gnome? I suspect it's Unity but please correct me if I'm wrong) then renamed the file to end with .desktop.desktop - not what I wanted. After a bit of messing around I guessed that Unity was automatically adding a file extension and managed to rename it so it ended with only one .desktop
How can I turn off automatic file extension renaming? Or is this the only filetype which has this annoying behaviour? In which case I can live with it. (But I'll be tutting a lot. ;-)
I'm used to renaming files, so unexpected behaviour in both Nautilus and Thunar is annoying and gets in the way of my completing simple tasks. Thunar is even worse - it doesn't show the file extension at all!
You are right, this is only with .desktop files. This was introduced a couple of releases ago to my knowledge, probably to make sure you don't break a starter/launcher.
Using the mv command via the command line does not have this issue, if you do need to rename the file.