Comment 4 for bug 640163

The capability to edit custom scripts has been removed from the codebase, and at this time is not planned to come back, so am marking this bug as a won't fix.

Greasemonkey got a major update a few years ago, which busted stock-replies fairly badly. I've done a rewrite of the script to get it functional once again. In the old script, a lot of it's code was devoted to the management and UI for custom scripts, making it challenging to debug (and maintain) the code. So, dropping this feature permitted majorly simplifying the code and thus making it a lot easier to debug (and hopefully to maintain). The old code's custom script functionality had some imperfections, such as the bug described here; it never did work quite right, and there wasn't an easy way to share (or backup) your customizations.

Ideally, I think a better solution for custom scripts would be to store them in a web app, where they could be loaded and saved via a REST API. A nearer-term solution would be a git repo the data can be loaded from and where collaborative editing of responses can be done. This latter idea I think may be in the works soon; the former idea is probably too blue sky, at least for now.