I used a gmail notifier application for a short period in time and it immediately took over my browser's mailto links. Everytime I would click on a mailto: link (which composes an email from a website) it would take me into gmail. I did not want this and wanted to use Thunderbird.
After doing some searching I found lots of links on how to set your gmail as your default email program but nothing to change it back to Thunderbird. So here it is.
Open firefox
1. Type about:config in the address bar.
2. Type network.protocol-handler.external.mailto and change the value to true by double clicking on it.
