Description:
When GEdit is running on one desktop, and on another desktop, e.g. a text
file is opened in Nautilus on another desktop, the GEdit window changes its
desktop to the current one. This destroys the work environment on the other
desktops.

To reproduce:
1. Open GEdit on Desktop 1
2. Open text file in GEdit
3. Switch to Desktop 2
4. Open Nautilus
5. Activate a text file that is associated with GEdit
6. Result: GEdit window comes to desktop 2, with both files open in tabs.

Expected Result:
The GEdit window should stay on Desktop 1, and another GEdit window should
open on Desktop 2. Alternatively, the GEdit window should stay on Desktop
1, and a new Tab with the file opens in it (this is very non-intuitive,
though.)

Reason why the behaviour is bad:
This feature destroys work environments on currently not active desktops.
For example, I open several files in GEdit on Desktop 1, editing a web
site. I switch to Desktop 2, and start to search through my template
library, opening them not as a Nautilus view, but in GEdit, because it's
better to browse. The mentioned behaviour fetches the GEdit window from
Desktop 1, with the files of my site; if I now erronaeously close this
GEdit window (because I just quickly previewed the file), then my whole
work environment on Desktop 1 is lost.