Directing Mailto: to Gmail

Open your Gmail page in a tab of firefox. In the address bar copy and paste the following:

javascript:window.navigator.registerProtocolHandler("mailto","https://mail.google.com/mail/?extsrc=mailto&url=%s","GMail")

After clicking on a mailto: link you will now get the option to direct the link to Gmail, Yahoo or your mail client. Choose Gmail.

**If this trick doesn't work, go into about:config and make sure that network.protocol-handler.external.mailto is set to its default value true**