the final part of my upgrade saga was installation of new nvidia drivers, which has in the past taken at least two days and required anguish, blood sacrifices to unknown demons, and angry outburts at anyone who encounters me. but i just now installed the nvisia drivers for ubuntu-16.04 and they . . . just worked! (the act of writing my particular configuration, primaty monitor below secondary monitor, won't write to the x.org configuration file, so i have to redo it on every reboot, but that's as it has always been.) now if i could cook up the mouse cursor i've wanted ever since i switched from OS/2 to linux. there was an OS/2 utility that allowed one to write one's own mouse (and other) cursors, and i got it and used it and loved it because it was possible to make a pointer arrow that was the reverse of whatever it was over -- black on white, white on black, blue on red, etc., to the point of even being half one color and half the other when it rested on an edge. this made it manifestly visible, always. linux has nothing to match it and i intend to undertake a course of study that will result in its being replicated for linux. i'll send postcards. -- dep Sent with ProtonMail Secure Email. Because privacy matters.