Opera's built-in source viewer gives you the ability to edit a locally saved web page. First, make the desired changes within the source code itself. Once you are satisfied you can click on the Apply changes button, located at the top of the source viewer, to save your code to cache and see your changes applied immediately. This can be extremely helpful for making changes on the fly. Please note that you can use the following keyboard shortcut in lieu of clicking the button: Ctrl + R.


