Using this plugin, every time you hit "save" on the gadget definition page, it adds a backslash (\) prior to any quote character. If you don't remember that you've already saved, and save again with the backslash inserted, it'll save it into the code and break the widget.
So this plugin works in WordPress 2.8, but not if you hit "Save" twice in a row by accident. If you do, delete the extra characters from the widget definition and save it again (once!).