When I go to a (any) website with Firefox Nightly v47.0a1 (2016-01-28) and try to save an image by right-clicking on my mouse and opting for "Save Image As...", the Firefox download manager still allows me to select a folder on my hard drive and/or change the name of the image I want to save, but when I press the "save" button (options "save" or "cancel"), nothing happens. That is, the save/cancel box disappears, but the image is not actually saved. This occurs since yesterday (27-1-2016) after Firefox Nightly's automatic upgrade to v47.0a1 (2016-01-27) was installed. I just installed today's version (28-01) and the bug is not fixed. When I close the Firefox Nightly Browser and then go to the regular Firefox browser v 44.0 (I can run both on my PC, obviously not simultaneously), the problem does not occur there.