Currently in order to make a change to your tagging script, you have to: click the options menu > click "Options..." > expand "Advanced" > click "Scripting"

This gets a bit tedious when making lots of minor changes and testing them.

It would be great if there was an option to just select a file on your filesystem.  Then you could just edit your script in your favourite text editor.  Much easier.  

Also means that people are less likely to lose their code if they don't happen to be backing up their Picard config.

Obviously it would be best if Picard re-read the script file every time it's executed in case of changes.

Another recent ticket ( https://tickets.metabrainz.org/browse/PICARD-404 ) requested the ability to allow for multiple scripts.  So maybe in this case, instead of a "Script filename" option, it could be a "Scripts folder" option, which would execute all scripts in that folder, in filename order I guess.