Mirror external HDMI/monitor output onto primary display automatically

Openbox autostart now detects any connected output beyond the primary and mirrors the kiosk content onto it via xrandr, instead of leaving detected-but-unused external displays dark. Also documents the behavior, its limitation (applies at session start, not live hotplug), and adds an HDMI troubleshooting section to the README.

Readme.md

@@ -378,6 +378,21 @@ id kiosk
 sudo -u kiosk DISPLAY=:0 xdpyinfo
 ```
 
+**External monitor/TV (HDMI) shows nothing:**
+```bash
+# List outputs and check if the external display is detected
+sudo -u kiosk DISPLAY=:0 XAUTHORITY=/home/kiosk/.Xauthority xrandr
+
+# Look for your output (e.g. HDMI1/HDMI2/HDMI-1) as "connected" with a mode list.
+# If it's "connected" but not active, autostart should mirror it automatically on
+# next login/boot. To apply immediately without rebooting:
+sudo systemctl restart lightdm
+
+# To test mirroring manually right now (replace names with what xrandr showed):
+sudo -u kiosk DISPLAY=:0 XAUTHORITY=/home/kiosk/.Xauthority xrandr --output HDMI2 --auto --same-as eDP1
+```
+If the output shows `disconnected`, it's a cabling/port/EDID issue, not software — try a different cable/port or a monitor known to work.
+
 **Audio not working:**
 ```bash
 # Check PipeWire (use menu: Advanced → Audio Diagnostics)
@@ -1122,6 +1137,7 @@ See the LICENSE file in the repository for full terms.
 **Current Version:** 1.0.3
 
 **Recent Updates (v1.0.3):**
+- **HDMI/external display mirroring:** autostart now detects any connected display beyond the primary (e.g. HDMI-out to a monitor/TV) and mirrors the kiosk output onto it automatically — previously the external output was left inactive even when detected by X
 - **Package install:** installer now also installs `net-tools` and `ncdu` (alongside the already-installed `curl` and `git`)
 - **Touch input fix (keyring):** added `--password-store=basic` to the Electron launch. Under LightDM autologin the GNOME keyring stays locked; when Chromium accessed it, the keyring unlock dialog grabbed all keyboard/touch input — the kiosk rendered fine but ignored every tap and keypress. This flag stops Electron from using the keyring, so the dialog never appears.
 - **Touch gesture fix (libinput):** any touch screen is now forced to the `libinput` driver via `/etc/X11/xorg.conf.d/99-finger-libinput.conf` (matched by hardware capability, so it works on any brand and never affects keyboards, mice, or the pen/stylus). Some drivers — notably `wacom` — only do single-touch pointer emulation and never pass real multitouch to Chromium, so 1-finger and 2-finger swipe gestures could not fire. libinput delivers proper multitouch.
@@ -1164,7 +1180,8 @@ See the LICENSE file in the repository for full terms.
 **Known Limitations:**
 - Raspberry Pi support untested in production
 - No web-based configuration (CLI menu only)
-- Single display only (extended desktop not supported)
+- Extended desktop not supported — additional connected displays (e.g. HDMI-out to a monitor/TV) are automatically **mirrored**, not extended
+- Display mirroring is applied at kiosk session start only — plugging in a display after boot requires restarting the display (`sudo systemctl restart lightdm`) or logging back in for it to pick up the new output
 
 ---
 

ubuntu-based-kiosk-v1.0.3.sh

@@ -7392,6 +7392,17 @@ TOUCHCFG
 sudo -u "$KIOSK_USER" tee "$KIOSK_HOME/.config/openbox/autostart" > /dev/null <<'AUTOSTART'
 #!/bin/bash
 
+# Mirror any connected external display (e.g. HDMI-out to a monitor/TV) onto
+# the primary display so the kiosk content shows on both.
+PRIMARY_OUTPUT=$(xrandr --query | awk '/ primary/{print $1; exit}')
+if [ -n "$PRIMARY_OUTPUT" ]; then
+  for OUT in $(xrandr --query | awk '/ connected/{print $1}'); do
+    if [ "$OUT" != "$PRIMARY_OUTPUT" ]; then
+      xrandr --output "$OUT" --auto --same-as "$PRIMARY_OUTPUT" 2>/dev/null
+    fi
+  done
+fi
+
 # AGGRESSIVE DPMS disable - multiple methods
 xset s off
 xset s noblank