I just installed the pgadmin3 package on an up-to-date Ubuntu 12.04 installation.
I thought pgadmin was repeatedly crashing, because I'd switch to another window and then when I used the application switcher (Alt-Tab), pgadmin wasn't listed, and then when I clicked the launcher icon, the program started all over again.
It took me a while to realize that I had multiple instances of pgadmin3 running!
I'm guessing this problem is caused by bug(s) in pgadmin3 or something wrong in the launcher setup, but I looked at the pgadmin3.desktop file and compared it the .desktop file for an app that works fine and saw nothing suspicious. I realize that pgadmin3 is not a Gnome app, but it is a GUI app included with Ubuntu and it should work with the default desktop (Unity, that is).
Thankfully, every instance of pgadmin does show up in the "window spread" (Super-W) view.
I guess for now I will have to adapt my habits to use Super-W instead of Alt-Tab (or clicking the active launcher icon).
Any ideas? Where should I file a bug? Under pgadmin3, Unity, or...?