(Ubuntu 11.10 Oneiric with Unity 3D)
In CompizConfig Settings Manager (CCSM) I activated the plugin Place Windows (? in German: Fenster platzieren) and configured it as follows:
This works perfectly for Thunderbird, but Firefox always opens the first window on the actually focused viewport and not where it should. A new window when Firefox is already running opens at the configured workspace, even if Firefox runs on another viewport.
The described Problem appears when I open Firefox out of the Dash or from the Launcher or listing it in Startup Applications (Command: /usr/bin/firefox). When I open it by clicking a link in Thunderbird everything runs as it should.
Furthermore: I started Firefox from the Launcher and switched to Expo mode (by pressing Workspace Switcher in Launcher). Then I saw appearing Firefox on the configured workspace for a split second before finally be opened on the focused viewport.
When I restart Firefox after a crash or when it didn't close correctly before (it starts then with what you see in about:sessionrestore) it opens on the configured viewport.
I found out that it works correctly when I set
Show my home page or
Show a blank page. Firefox opens on the focused viewport and not where it should when this is set to
Show my windows and tabs from last time.