Comment 9 for bug 1429153

Same bug here.

Fred solution works, but it is not optimal for users who use dash to dock extension, because it always run gedit in new instance on dock (dash), to solve that problem, simply rename gedit.desktop to org.gnome.gedit.desktop (should not matter really, it should work with any other name) from nautilus (or terminal), and then, run it, add to favorites, and all new instances should be under same item.

Only thing is, in order to run it from nautilus, you need to re-select "new" gedit, and it will work as fine and integrated as it should.