About
Tab Preview is an extension for Firefox 1.5 or newer that shows a preview of tab contents when you move your mouse over a background tab. It's simple to use, but surprisingly useful.
Install and try it out!
Also check out the options available. Go to the Tools -> Extensions menu, click on the Tab Preview entry, and click the Options button.
Technical Info
Tab Preview uses the drawWindow method of the HTML canvas element defined in the WHAT-WG spec. This is implemented in Firefox 1.5 or newer.
Please note that if you build your own Firefox from source, you'll need to have --enable-canvas in your build configuration. You can check to see if this is the case by typing about:buildconfig into the URL bar. If you see an empty gray box instead of a preview, this is probably the case. (Gentoo users can reportedly add the "mozsvg" USE flag.)
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