Always-On HDMI Displays

Creating a bug report/issue

I have searched the existing open and closed issues

Required Information

  • DietPi version = 8.25.1
  • Distro version = Bookworm 0
  • Kernel version = Linux ee-pi 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
  • Architecture = arm64
  • SBC model = RPi 4 Model B (aarch64)
  • Power supply used = Original Raspberry Pi 4
  • SD card used = SanDisk 16GB

Additional Information (if applicable)

My Issue

Hi everyone,

I want to build a “Kiosk”-Like System, which displays two Firefox-Windows in Fullscreen, with different content on two HDMI Displays, which both run at 1080p. To control it, I want to connect to the Pi using TigerVNC.

With dietpi, I managed to get most of this running great, with one exception:
When the Pi is booting while not both monitors are connected or switched on, the display manager seems to fall back to single-desktop mode. When both monitors are turned on after the boot sequence is initiated, it seems to start in some kind of “two separate X desktops” mode.
I always need to manually reconfigure the dual-monitor desktop in these situations.

(How) is it possible to always have these two Desktops activated, independent of the hardware monitor’s state?