works well for me, but its missing some of the actions in the legacy addon I used for years til it broke after firefox 52. This was called Context Menu Image Saver by choobin, it had a pull down in options for "if the image exists the save action will be": 1. prompt user, (giving the choices rename or overwrite), 2. save as a unique file, (rename). or 3. overwrite the existing file. This worked brilliantly for all situations, Please incorporate this feature if you can, Regards.
However, it does support manually setting the option, which - if I understand correctly - is what the extension you mentioned does. This should be fairly simple to implement, so I'll have a go at it soon!
