Thunderbird problem after update

[gilloz]

After updating my Ubuntu through the Update Manager, I have lost the capability of minimizing any emails in the sense that the tab in the upper Left hand corner portion of the panel no longer appears. The email that I minimize only goes behind the main Thunderbird window. I have to grab and drag the main window down to expose the minimized window. How can I get the minimized tab back in the upper panel of my Ubuntu desktop. I am still using 7.10 version.

Note: The update was a routine update for Ubuntu 7.10 only.