Rated 5 out of 5 stars

IT DOES SUPPORT ADD-ONS! There is a workaround: (1) When you go to download the add-on you want, right-click and choose "Save link as" and save it to your desktop (2) Click on the bottom-right gears button of the prism window, (3) Hover on Tools > click on Add-ons... (4) Click the Extensions tab (5) Drag the .xpi file of the add-on over the window and drop it, (6) and the rest is history. AWESOME ADD-ON!!!

This review is for a previous version of the add-on (1.0b1).