Do you find it annoying to have to click on the small cross to close a tab? Now with Fast Close Tabs you can just click on the upper right cross of the window to close the active tab.
No more need to precisely point at the tab close cross. No need to check if you are in a tab or a window before closing it. Streamlines the user experience, by example for users not familiar with tabs.
Tip: clicking in the top right corner (not just the cross) of your screen will usually close the current window, if it is maximized. With Fast Close Tabs, it will close the active tab.
The ALT+F4 shortcut will also close the active tab.
Since version 1.1, you can add a button to close the whole window. Use the "Customize" Firefox command (by right clicking on a toolbar) to add it where you want.
Since version 1.2, it works with Thunderbird 3.0.
Please let a comment if you like it.