Mozilla recently released Thunderbird 11. It's an excellent mail client, but one change they made was to move tabs above the toolbar. It's not a huge difference, but it makes things a little tricky when you have tab positions in muscle memory. Thankfully there's a quick solution in the form of an addon called "rise of the tools". It's quick to install, and doesn't even require a restart of Thunderbird.
How to Install in Rise of the Tools in Thunderbird 11:
- Download and save the file to your hard disk.
- In Mozilla Thunderbird, open Add-ons from the Tools menu.
- From the options button next to the add-on search field, select "Install Add-on From File…" and locate the downloaded add-on