It's a freeware Windows utility called Push That Freakin' Button
(PTFB). Drag the PTFB finger over a button on any annoying dialog, and
it will automatically close it for you from now on.
Actually it is meant to work with standard Windows widgets, which
Firefox does not use. But the PTFB author has cleverly supplied a way
to push non-standard widgets: when you drag the PTFB finger over the
button, hold down *both* mouse buttons - this will tell PTFB to click
Using this technique, you can make PTFB work with Firefox (or any
other web browser) !!!!! Goodbye annoying login screens !!!!!