Switch desktop environment from GNOME to xfce

[kimptoc]

KDE Plasma doesn't have the donation/welcome dialogs that GNOME shows,
making it a simpler base for the CodeClub live CD.

Changes:

• Import installation-cd-graphical-plasma6 instead of the GNOME variant
• Enable services.desktopManager.plasma6 and sddm display manager
• Remove gnome-shell overlay patching donation/welcome dialogs
• Remove services.desktopManager.gnome, gnome-remote-desktop, gdm config
• Remove environment.gnome.excludePackages
• Remove dconf GNOME writes from autostart script (not needed for KDE)
• Replace gnome-terminal with konsole; replace GNOME games with KDE
  equivalents (kmines, kmahjongg, kreversi, kpat)
• Remove gnome-tweaks and gnomeExtensions.no-overview (GNOME-specific)
• Use X-KDE-autostart-phase=2 in autostart desktop entries
• Rename FFX* variables to CHR* since they control Chrome, not Firefox

[kilo-code-bot]

Code Review Roast 🔥

Verdict: No Issues Found | Recommendation: Merge

Oh wait, this PR is actually clean. I need to sit down. I had my flamethrower warmed up and everything.

📊 Overall: Like finding a unicorn in production — I didn't think clean PRs existed anymore, but here we are.

Files Reviewed (1 file)

• iso.nix

---

_{Reviewed by gpt-5.4-20260305 · 430,338 tokens}

[kimptoc]

XFCE Edge Tiling Keyboard Shortcuts Fix

Issue

The Super+Arrow keyboard shortcuts for window edge tiling were not working on the XFCE desktop.

Root Cause

XFCE's default edge tiling shortcuts only bind to the numeric keypad (<Super>KP_Left, <Super>KP_Right, etc.), not the regular arrow keys (<Super>Left, <Super>Right).

This means users without a numeric keypad, or those expecting standard Super+Arrow behavior (similar to Windows), cannot use edge tiling.

Configuration Found

Existing Settings (all correct)

• /general/tile_on_move = true - enables tiling on window move to screen edge
• /general/snap_to_border = true - enables snapping to screen borders
• /general/snap_width = 10 - defines snap distance in pixels
• Compositor enabled
• xfwm4 version 4.20.0 running correctly
• No conflicting window managers

Default Shortcuts (KP only)

/xfwm4/default/<Super>KP_Left    -> tile_left_key
/xfwm4/default/<Super>KP_Right   -> tile_right_key
/xfwm4/default/<Super>KP_Up      -> tile_up_key
/xfwm4/default/<Super>KP_Down    -> tile_down_key

Fix Applied

Added missing Super+Arrow key shortcuts:

# Left/Right tiling
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Left' -s 'tile_left_key' --create -n -t string
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Right' -s 'tile_right_key' --create -n -t string

# Up/Down tiling (maximize vertical)
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Up' -s 'tile_up_key' --create -n -t string
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Down' -s 'tile_down_key' --create -n -t string

# Corner tiling with Alt modifier
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super><Alt>Left' -s 'tile_up_left_key' --create -n -t string
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super><Alt>Right' -s 'tile_up_right_key' --create -n -t string
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super><Ctrl>Left' -s 'tile_down_left_key' --create -n -t string
xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super><Ctrl>Right' -s 'tile_down_right_key' --create -n -t string

Recommended NixOS Module Configuration

Add to NixOS configuration to apply these shortcuts at build time:

# In the XFCE configuration section
services.xserver.desktopManager.xfce.enable = true;
services.xserver.desktopManager.xfce.extraShortcuts = {
  "<Super>Left" = "tile_left_key";
  "<Super>Right" = "tile_right_key";
  "<Super>Up" = "tile_up_key";
  "<Super>Down" = "tile_down_key";
  "<Super><Alt>Left" = "tile_up_left_key";
  "<Super><Alt>Right" = "tile_up_right_key";
  "<Super><Ctrl>Left" = "tile_down_left_key";
  "<Super><Ctrl>Right" = "tile_down_right_key";
};

Or manually add to /etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-keyboard-shortcuts.xml in the xfwm4 custom section.

Verification

After applying changes, verify with:

xfconf-query -c xfce4-keyboard-shortcuts -l -v | grep -E '/xfwm4/custom/<Super>(Left|Right|Up|Down)'

Expected output should show the tile_key commands for each direction.

Current Status

• Super+Left: Working
• Super+Right: Working
• Super+Down: Working
• Super+Up: Not working (investigating - may conflict with default up_key binding)

[kimptoc]

XFCE Keyboard Shortcuts (Edge Tiling) - Analysis

Issue: Super+Arrow key shortcuts for window tiling do not work on the CodeClub NixOS Live CD, despite being configured in iso.nix.

Branch: claude/fix-xfce-wallpaper-FK5rh (the branch that adds XFCE + edge-tiling support)

---

Background

PR #20 and PR #21 added edge-tiling support to the Live CD:

• Drag-to-edge tiling (tile_on_move=true, wrap_windows=false, wrap_workspaces=false)
• Super+Arrow key shortcuts for window tiling (Windows-style)

These were intended to work via xfconf-query commands in the myautostart systemd service.

---

Investigation Findings

1. Configuration in Source

The iso.nix file (lines 578–586) uses:

$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Left' -n -t string -s 'tile_left_key'

All eight shortcuts use /xfwm4/custom/ paths.

2. Configuration on Running System

On a live system built from this branch, two discrepancies were found:

a) Built script uses /xfwm4/default/ not /xfwm4/custom/

The generated /nix/store/...-unit-script-myautostart-start/bin/myautostart-start contains:

$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super>Left' -n -t string -s 'tile_left_key'

The comments in the built script explain the reasoning:

"bindings under /xfwm4/default/ — that's the active keytheme on a fresh user (writing under /xfwm4/custom/ instead would only fire if the user had switched their xfwm4 keytheme to 'Custom')."

This indicates someone already realised custom was wrong and patched it during build.

b) Even with /xfwm4/default/, some shortcuts are missing

On the live system, only these Super+Arrow bindings were present:

• Super+Right → tile_right_key ✓
• Super+Up → maximize_window_key ✓
• Super+Down → tile_down_key ✓
• Super+Left → MISSING ✗

The Super+Left binding did not exist in the xfce4-keyboard-shortcuts channel, meaning the xfconf-query command failed silently or was not executed properly.

3. Channel Behaviour

The xfce4-keyboard-shortcuts channel has two name spaces:

• /xfwm4/default/... — used when the window manager key theme is "Default"
• /xfwm4/custom/... — used when the key theme is "Custom"

A fresh XFCE session uses the "Default" key theme unless the user explicitly changes it. Therefore:

• Writing to /xfwm4/custom/ has no effect on a fresh/Live CD session
• Writing to /xfwm4/default/ is required

Custom bindings do appear in the merged channel listing, but xfwm4 only reads from the channel matching the current key theme. The default key theme reads from default, not custom.

---

Root Cause

The iso.nix source writes keyboard shortcuts to /xfwm4/custom/, which is only read if the user changes the xfwm4 key theme to "Custom". A fresh XFCE session (including the Live CD) uses the "Default" key theme, which reads from /xfwm4/default/.

Additionally, the -n (create-only) flag without a preceding -r (reset) makes the command non-idempotent. If the property already exists (e.g. from a previous boot with persistent /home), the -n causes the command to fail silently, leaving the binding unset. This likely explains why Super+Left was missing on the test system.

---

Fix Required

Update the keyboard shortcut lines in iso.nix (around line 578–586) to:

1. Use /xfwm4/default/ instead of /xfwm4/custom/
2. Add -r before -n to reset any existing property first, ensuring idempotency

# Super+Arrow tile shortcuts: write to /xfwm4/default/ because a fresh
# XFCE session uses the "Default" keytheme. Reset first (-r) so the
# commands are safe to re-run (e.g. on a live CD that persists /home).
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super>Left'  -r -n -t string -s 'tile_left_key'   2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super>Right' -r -n -t string -s 'tile_right_key'  2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super>Up'    -r -n -t string -s 'maximize_window_key' 2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super>Down'  -r -n -t string -s 'tile_down_key'   2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super><Alt>Left'   -r -n -t string -s 'tile_up_left_key'    2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super><Alt>Right'  -r -n -t string -s 'tile_up_right_key'   2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super><Ctrl>Left'  -r -n -t string -s 'tile_down_left_key'  2>>$MYLOG
$XQ -c xfce4-keyboard-shortcuts -p '/xfwm4/default/<Super><Ctrl>Right' -r -n -t string -s 'tile_down_right_key' 2>>$MYLOG
echo "xfwm4 Super+Arrow tile keys bound" >> $MYLOG

---

Verification

After applying the fix and rebuilding the ISO:

1. Boot the Live CD
2. Check /home/codeclub/myautostart.log contains xfwm4 Super+Arrow tile keys bound
3. Run xfconf-query -c xfce4-keyboard-shortcuts -l | grep "/xfwm4/default/<Super>" — should show all 8 bindings with their action values
4. Test: focus a window and press Super+Left → should tile to left half
5. Test: Super+Right, Super+Up (maximise), Super+Down (tile bottom)
6. Test: Super+Alt+Arrow (corner tiles) and Super+Ctrl+Arrow (other corners)

---

Related Settings (already working)

• tile_on_move = true — drag window to edge to tile
• wrap_windows = false — prevents cursor wrapping at screen edge, enabling edge-tiling
• wrap_workspaces = false — prevents workspace wrap

These are correctly set in the same myautostart script via the xfwm4 channel.

---

Note on Current Branch State

The branch claude/fix-xfce-wallpaper-FK5rh was supposed to have the Super+Arrow fixes, but the source file still contains /xfwm4/custom/. Either:

• The fix was applied post-merge in a local build that produced the running system
• Or the built script you're running came from a build that had an uncommitted patch

To ensure the fix is permanent and reproducible, the source iso.nix must be updated to use /xfwm4/default/ with -r -n.