If you want to open the source code in an editor of your choice you can change two hidden settings. Type '''about:config''' into the location bar. Accept the warning message that pops up, this brings up a lot of settings. You then need to change 2 of the settings that appear, for details on the 2 settings see [http://kb.mozillazine.org/View_source.editor.external view_source.editor.external] and [http://kb.mozillazine.org/View_source.editor.path View_source.editor.path] You can also change those 2 settings by using an add-on such as [https://addons.mozilla.org/en-US/firefox/addon/394/ Dafizilla ViewSourceWith]