Display manager for Pi 4B?

I (finally!) managed to get two ThinkVision L192p Flat Panel Monitors running on the Pi 4B with Patchbox, but only after performing (yet) another surgery on the thick acrylic Pisound box to allow the mini-HDMI cables to make proper contact. Bonus: more airflow.

The problem I have now is that Patchbox’s default-display-manager lacks GUI dual monitor management, as in Ubuntu and Raspbian, so the main screen is mirrored to the second. How can this be changed to having the secondary screen as an extended display (i.e. Not a mirror of the primary)?

Best I’ve seen so far is How to Set Up Multiple Monitors in Linux, but… Gak! Is there a simpler way of adding GUI monitor management to handle this more gracefully? Ideally, any prospect of updating PatchboxOS to include dual-monitor use?

Well, I tried installing GDM3 but the system crashed with a blank screen when it tried to load the Desktop Manager. So that won’t work on a Pi4B 4GB RAM.

The ability to have an extended desktop on two monitors would be an advantage to people running Patchbox OS on a Pi4. I request this as for a future update.

I haven’t yet looked into multi-monitor use of Pi 4, so I can’t help you out, but anyway - as Patchbox OS is based on Raspberry Pi OS and it itself is based on Debian, every bit of information meant for RPi OS or Debian applies to Patchbox OS too. The solution to this should come from Raspberry Pi OS or Debian.

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Hi Giedrius,

Thanks for responding. The problem is that although based on Raspbian, PatchboxOS doesn’t have Screen Configuration in Raspberry Pi → Preferences → Raspberry Pi Configuration → Display as does Raspbian, so there’s no control of two monitors.

I think that as more people run Pi 4s, they would appreciate being able to control this in PatchboxOS.


The following steps allows two monitors in Patchbox)S on a Raspberry Pi 4B 4GB RAM:

sudo apt install xrandr
(Installs Screen Configuration in Pi menu → Preferences)
sudo apt upgrade
sudo apt dist-upgrade

The monitors were recognised at boot with the second as an extended desktop. Both monitors (HDMI 1 and HDM! 2) show up in Appearance Settings.

Xrandr -q shows a list of possible resolutions for each monitor.