I just upgraded from Ubuntu 11.10 to 12.04 and now Thunderbird is not being "managed" properly in the launcher bar.
It used to be that an application in the launcher bar that had been started would then just have a little triangle to the left of the icon that is used to start the application.
Now, when I start Thunderbird, I get two Thunderbird icons in the launcher bar - one to start Thunderbird (permanent and unchanged) and one showing that it is running (with the little triangle to the left).
I'm not seeing this behaviour with any other applications. For example, FireFox works correctly and as it did with Ubuntu 11.10 as do LibreOffice Writer and Calc, Terminal, gedit, nautilus.
I've tried removing Thunderbird from the launcher bar and re-adding it but it made no difference.
Thunderbird 12.0.1
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