Unsuccessful Rated 1 out of 5 stars
"Another option for making DDU compatible with FF4 is to install the add-on Add-on Compatibility Reporter. This will allow you to enable DDU, and to test any other disabled add-ons for compatibility." -jwilk
Thanks for the tip. However, this does not work after installing on my Macintosh. Dragdropupload is still incompatible with FF4.