Running 12.10/KDE on a laptop (Intel 3000 graphics) with an external 1920x1080 monitor, I wanted to use the display settings widget to get the screen to "blink" in order to get rid of an increasingly annoying tendency of ... well I don't know what's doing it, but something keeps getting screwed up with cursors in terminal and GVim windows; it's like the cursor stepped in wet paint.
So anyway I brought up the display settings tool and told it to switch to 1600x900, and it did. Then I tell it to switch back, and it does nothing at all. I tell it to reenable the laptop's own screen and click "Apply", and nothing happens. I tried the XFCE tool to do the same thing, and it behaves identically.
I switched to the console to look at the X log, and it's getting the an "Invalid argument" error from something. Eventually it got so wedged up that I just killed the X server; it worked upon restarting.
I think what was happening was that the tool was requesting a switch to a resolution for which the server couldn't find an appropriate modeline. I don't really know what to do about that or how to do something to un-confuse the UI tools. I know there must be an old-school X cli tool to make the requests explicitly to the server. Is that true? Is there some KDE "innards" config file that could be repaired?
Bonus: what's up with that cursor problem? It's not happening now that I've rebooted. I suspect it may have something to do with the fancy window effects; I'll try disabling those.
edit looks like
xrandr is what I was thinking of. I only have to remember that like once every two or three years :-)