like many, i have .jpg/.gif/et.al. mapped to open with Preview, and .txt mapped to open with TextEdit. seemingly randomly, these file associates will change to some other app. i've detected no pattern with regard to when they get changed, or to what app. once i fix it (command-i, Open with.., Change All...), it stays fixed for a while. has anyone else encountered this and know how to fix it? i'm on OSX 10.11.6 (el cap), MacBook Pro (Retina, 13-inch, Early 2015). EDIT: there is a workaround! the workaround is to NOT drag/drop images from FF, but right click and save. EDIT 2: there is a solution!