I am using the Ubuntu Netbook Remix. When I boot up in netbook mode and start an application from the menu multiple times, the application starts only once and any further attempts of starting the application another time only switch focus to the window of the first running instance.
But here is a strange thing I observed: When I switch to desktop mode with the switching-applet of the netbook remix, I can start multiple instances just as expected. Even after switching back to netbook mode, this behavior persists.
I would like this to be the default behavior after booting.
edit, found solution: After comparing the tasklists in both modes I was sure that the problem is connected to the netbook-laucher applet, which I thought was just a frontend for the gnome-laucher. But it is not, I found this:
It explains that the described behavior is a "feature" and that it can be disabled by using:
gconftool --type=boolean --set /apps/netbook-launcher/disable_single_instance true