On 08/21/15 19:05, Neal Becker wrote:
At work I have laptop + external (hdmi) screen.
Yesterday I went home, woke laptop from sleep, and had no panel. Previously panel always went with 'primary' display, which was laptop with no external monitor, and external when connected. Which worked fine.
I tried logoff/logon, then reboot. Didn't fix it.
So I re-added panel, carefully setup as I wanted.
Today I connected external monitor. Now each display has it's own panel.
This happened to me one time a while back. What I found was that in "System Settings--->Hardware--->Display and Monitor--->Display Configuration" somehow one monitor was squarely on top of the other one. I just moved it to the "proper" configuration and everything was OK. Never found out what caused it and it hasn't happened again.