You can get some info here, maybe you can find additional
http://standards.freedesktop.org/des...ec-latest.html
You can also open existing installed ones to get somen idea's ect.
I tend to work out just using some logical trial & error, don't think I've needed StartupNotify=true for StartupWMClass to be effective but generally that line isn't an issue
If you're going to spend much time with .desktops and or quicklists ect. you may want to set up a nautilus action or 2
I always put in 2 right away on a new install -
Open desktop file
Open desktop file as Root
NA lets you set an action using basename so the above will only show in the context menu for .desktop's
Bookmarks