Problem solved. Thanks, Allen! That gave me the nudge I needed to get this the rest of the way figured out.
In case anyone's reading this in the future, here are the problem and how I fixed it. Installing and running xrandr in a terminal window yielded a line like Screen 0: minimum 800 x 600, current 7680 x 3240, maximum 8192 x 8192 > Problem: that 8192-pixel maximum width prevents the monitor layout I desire. Solution: Create a new xorg.conf file by (mostly) following the instructions at https://wiki.debian.org/Xorg#What_if_I_do_not_have_a_xorg_config_file.3F - $ sudo passwd # set up a root password - (Switch to a console via Ctrl+Alt+F1) - $ su # log in as root - # /etc/init.d/lightdm stop - # cd /etc/X11 - # Xorg -configure # This creates a new file in /root/xorg.conf.new - # cp /root/xorg.conf.new /usr/share/X11/xorg.conf.d/99-steve-custom.conf - (log out as root with Ctrl+D) - $ shutdown now -r Originally, I'd edited the file to include "Virtual 9600 2160" in each of the "Display" subsections - as suggested by https://wiki.ubuntu.com/X/Config/Resolution#Setting_resolution_changes_in_xorg.conf_--_resolution_lower_than_expected - but it still worked fine when I later removed those lines. After the restart, I was able to use Xfce's regular GUI Display tool to put the monitors side-by-side. Success! The first line of output from xrandr is now Screen 0: minimum 8 x 8, current 9600 x 2160, maximum 32767 x 32767 > Much better. I just hope nothing ever decides to display at that new minimum size. :) On Fri, Sep 6, 2019 at 10:43 PM Allen <[email protected]> wrote: > Have you tried ARandR? I always use it when I have two monitors... > > On 09/06/2019 05:09 PM, Steve McClellan wrote: > > Hi there. > > I'm trying to configure my monitors on my Xubuntu 18.04.3 (64-bit) > installation. > > I have two 4k monitors and a 2k monitor that I'm trying to use to display > an extremely wide (9600x2160) desktop. > > However, when I enter the display settings and configure the monitors > horizontally, the right side of the rightmost monitor goes blank. > > The tip of the mouse pointer won't go into the blank area (as the edge of > the blank area seems to be the edge of the desktop), but if the tip is at > the far right of the desktop, the rest of the pointer is visible in the > blank area. > > Some tinkering suggests that anything to the right of 7680 horizontal > pixels is blanked out. > > If I rearrange the displays such that one is above the others (and, > therefore, the full desktop is no more than 7680 pixels wide), all three > monitors work perfectly. But that's not the configuration I want. > > A bunch of googling didn't give me any ideas. > > Is there a maximum-desktop-width limit somewhere in the stack that I'm > brushing up against, or is there some weird problem with my specific setup? > > Thanks, > Steve McClellan > > > > -- > xubuntu-users mailing list > [email protected] > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/xubuntu-users >
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