LXDE: add Custom packages option and respect existing display manager

- New 'LXDE Custom (Choose packages)' menu entry: fixed base
  (lxde-core + xserver-xorg, lightdm only when no display manager
  is configured) plus a data-driven checklist of 16 extras.
- lxterminal, polkitd, notification-daemon and light-locker stay out
  of the checklist: they arrive via lxde-core Recommends (verified
  against packages.debian.org/trixie, 2026-10-16).
- Full/Core/Custom now honor an already-configured display manager
  via _existing_display_manager (GNOME/KDE pattern): no debconf
  preseed, no lightdm install, no enable over an existing DM.
- Extract _select_packages_checklist helper to utils.sh; XFCE
  Custom consumes it with no functional change.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

modules/desktops/desktop_lxde.sh

@@ -9,7 +9,8 @@ lxde_menu() {
         local -a lx_items=()
         lx_items+=("1" "LXDE (Full Desktop)")
         lx_items+=("2" "LXDE Core (Minimal Install)")
-        lx_items+=("3" "Back")
+        lx_items+=("3" "LXDE Custom (Choose packages)")
+        lx_items+=("4" "Back")
         local choice
         choice=$(_menu "LXDE" \
             "Select an option:" $TUI_ALTO $TUI_ANCHO $TUI_ALTO_LISTA \
@@ -19,27 +20,140 @@ lxde_menu() {
         case "$choice" in
         1) _install_lxde_full ;;
         2) _install_lxde_core ;;
-        3) break ;;
+        3) _install_lxde_custom ;;
+        4) break ;;
         esac
     done
 }
 
 _install_lxde_full() {
-    echo -e "${GREEN}Installing LXDE (Full) + LightDM...${NC}"
+    # Pre-apply summary: confirm the selection before any
-    echo "lightdm shared/default-x-display-manager select lightdm" | sudo debconf-set-selections
+    # debconf or apt transaction starts.
+    _confirm_install_list "LXDE Full Desktop" lxde lightdm || return
+
+    echo -e "${GREEN}Installing LXDE (Full Desktop)...${NC}"
+
+    # Keep an already-configured display manager intact.
+    local target_dm="lightdm"
+    local keep_dm
+    keep_dm=$(_existing_display_manager)
+    if [ -n "$keep_dm" ] && [ "$keep_dm" != "lightdm" ]; then
+        echo -e "${YELLOW}Display manager '${keep_dm}' is already configured — keeping it as default.${NC}"
+        target_dm="$keep_dm"
+    fi
+    echo "${target_dm} shared/default-x-display-manager select ${target_dm}" | sudo debconf-set-selections
+    _ensure_apt_updated
+    if [ "$target_dm" = "lightdm" ]; then
         _run_cmd "LXDE Full" "sudo apt install -y lxde lightdm" \
             "Installing LXDE (Full Meta Package) + LightDM..."
         sudo systemctl enable lightdm
-    echo -e "${GREEN}LXDE installed. LightDM enabled.${NC}"
+    else
+        _run_cmd "LXDE Full" "sudo apt install -y lxde" \
+            "Installing LXDE (Full Meta Package)..."
+    fi
+    # Selection confirmed once above; release the
+    # per-package prompt suppression.
+    _SELECTION_CONFIRMED=0
+    echo -e "${GREEN}LXDE installed. Default display manager: ${target_dm}.${NC}"
     _offer_pipewire_after_desktop
 }
 
 _install_lxde_core() {
-    echo -e "${GREEN}Installing LXDE Core + LightDM...${NC}"
+    # Pre-apply summary: confirm the selection before any
-    echo "lightdm shared/default-x-display-manager select lightdm" | sudo debconf-set-selections
+    # debconf or apt transaction starts.
+    _confirm_install_list "LXDE Core" lxde-core lightdm || return
+
+    echo -e "${GREEN}Installing LXDE Core (Minimal)...${NC}"
+
+    # Keep an already-configured display manager intact.
+    local target_dm="lightdm"
+    local keep_dm
+    keep_dm=$(_existing_display_manager)
+    if [ -n "$keep_dm" ] && [ "$keep_dm" != "lightdm" ]; then
+        echo -e "${YELLOW}Display manager '${keep_dm}' is already configured — keeping it as default.${NC}"
+        target_dm="$keep_dm"
+    fi
+    echo "${target_dm} shared/default-x-display-manager select ${target_dm}" | sudo debconf-set-selections
+    _ensure_apt_updated
+    if [ "$target_dm" = "lightdm" ]; then
         _run_cmd "LXDE Core" "sudo apt install -y lxde-core lightdm" \
             "Installing LXDE Core (Minimal) + LightDM..."
         sudo systemctl enable lightdm
-    echo -e "${GREEN}LXDE Core installed. LightDM enabled.${NC}"
+    else
+        _run_cmd "LXDE Core" "sudo apt install -y lxde-core" \
+            "Installing LXDE Core (Minimal)..."
+    fi
+    # Selection confirmed once above; release the
+    # per-package prompt suppression.
+    _SELECTION_CONFIRMED=0
+    echo -e "${GREEN}LXDE Core installed. Default display manager: ${target_dm}.${NC}"
+    _offer_pipewire_after_desktop
+}
+
+_install_lxde_custom() {
+    # Fixed base (not selectable); extras chosen from the checklist.
+    # lxterminal, polkitd, notification-daemon and light-locker are
+    # intentionally absent: they arrive via lxde-core's Recommends
+    # (verified on packages.debian.org/trixie, 2026-10-16).
+    local cleaned
+    cleaned=$(_select_packages_checklist "LXDE Custom" \
+        "Select the extra LXDE packages to install:" \
+        "lxappearance|Theme/appearance config" \
+        "lxappearance-obconf|Openbox theme settings" \
+        "lxrandr|Monitor configuration" \
+        "lxinput|Keyboard/mouse settings" \
+        "lxsession-edit|Session editor" \
+        "lxhotkey-gtk|Keyboard shortcuts config" \
+        "lxde-icon-theme|LXDE icon theme" \
+        "gpicview|Image viewer" \
+        "xarchiver|Archive manager" \
+        "galculator|Calculator" \
+        "mousepad|Text editor" \
+        "lxpolkit|PolicyKit authentication agent" \
+        "lxtask|Task manager" \
+        "numlockx|Enable NumLock on startup" \
+        "network-manager-applet|NetworkManager applet" \
+        "gnome-disk-utility|Disk utility")
+    [ -z "$cleaned" ] && return
+    # BH-004: reparse the space-separated selection into an array.
+    local -a lxde_pkgs=()
+    local _pkg
+    while IFS= read -r _pkg; do
+        [ -n "$_pkg" ] && lxde_pkgs+=("$_pkg")
+    done < <(echo "$cleaned" | tr ' ' '\n')
+    if [ ${#lxde_pkgs[@]} -eq 0 ]; then
+        _msg "LXDE Custom" "No extra packages selected — installing the\nfixed base only (equivalent to LXDE Core)." 10 60
+    fi
+
+    # Fixed base: lxde-core + xserver-xorg always; lightdm only
+    # when no display manager is configured yet — never force it
+    # over an existing one.
+    local -a base_pkgs=(lxde-core xserver-xorg)
+    local install_dm=0 keep_dm
+    keep_dm=$(_existing_display_manager)
+    if [ -z "$keep_dm" ]; then
+        base_pkgs+=(lightdm)
+        install_dm=1
+    else
+        echo -e "${YELLOW}Display manager '${keep_dm}' is already configured — keeping it as default.${NC}"
+    fi
+
+    # Pre-apply summary: confirm base + selection before any
+    # debconf or apt transaction starts.
+    _confirm_install_list "LXDE Custom" "${base_pkgs[@]}" "${lxde_pkgs[@]}" || return
+
+    if [ "$install_dm" -eq 1 ]; then
+        echo "lightdm shared/default-x-display-manager select lightdm" | sudo debconf-set-selections
+    fi
+    _ensure_apt_updated
+    _run_cmd "LXDE Custom" "sudo apt install -y ${base_pkgs[*]} ${lxde_pkgs[*]}" \
+        "Installing LXDE base + selected packages..."
+    if [ "$install_dm" -eq 1 ]; then
+        sudo systemctl enable lightdm
+    fi
+    # Selection confirmed once above; release the
+    # per-package prompt suppression.
+    _SELECTION_CONFIRMED=0
+    echo -e "${GREEN}LXDE installed (base: ${base_pkgs[*]}).${NC}"
     _offer_pipewire_after_desktop
 }

modules/desktops/desktop_xfce.sh

@@ -51,27 +51,28 @@ _install_xfce_wayland() {
 }
 
 _install_xfce_custom() {
-    local -a items=()
+    # BH-004: helper returns a space-separated selection;
-    for pkg in thunar xfdesktop4 xfwm4 xfce4-panel xfce4-terminal \
+    # reparsed into an array to avoid word splitting and injection.
-        xfce4-screenshooter ristretto mousepad xfce4-session \
-        xfce4-settings xfce4-power-manager; do
-        items+=("$pkg" "$pkg" "$(_state "$pkg")")
-    done
-    local choices
-    choices=$(_checklist "XFCE Custom" \
-        "Select the XFCE packages to install:" $TUI_ALTO $TUI_ANCHO $TUI_ALTO_LISTA \
-        "${items[@]}")
-    [ -z "$choices" ] && return
     local cleaned
-    cleaned=$(echo "$choices" | tr -d '"')
+    cleaned=$(_select_packages_checklist "XFCE Custom" \
+        "Select the XFCE packages to install:" \
+        "thunar|File manager" \
+        "xfdesktop4|Desktop manager" \
+        "xfwm4|Window manager" \
+        "xfce4-panel|Panel" \
+        "xfce4-terminal|Terminal emulator" \
+        "xfce4-screenshooter|Screenshot tool" \
+        "ristretto|Image viewer" \
+        "mousepad|Text editor" \
+        "xfce4-session|Session manager" \
+        "xfce4-settings|Settings manager" \
+        "xfce4-power-manager|Power manager")
     [ -z "$cleaned" ] && return
-
-    # BH-004: Convert to array to avoid word splitting and injection.
     local -a xfce_pkgs=()
+    local _pkg
     while IFS= read -r _pkg; do
         [ -n "$_pkg" ] && xfce_pkgs+=("$_pkg")
     done < <(echo "$cleaned" | tr ' ' '\n')
-
     # Pre-apply summary: confirm the selection before
     # the batch apt transaction starts.
     _confirm_install_list "XFCE Custom" "${xfce_pkgs[@]}" || return

modules/utils.sh

@@ -805,6 +805,28 @@ _confirm_install_list() {
     return 1
 }
 
+# Show a multi-select checklist of packages and return the
+# selection as a space-separated string ("" on cancel/Esc).
+# Args: title prompt "pkg|description" [pkg|description ...]
+# Already-installed packages are pre-checked via _state.
+_select_packages_checklist() {
+    local title="$1" prompt="$2"
+    shift 2
+    local -a items=() entry
+    for entry in "$@"; do
+        local pkg="${entry%%|*}"
+        items+=("$pkg" "${entry#*|}" "$(_state "$pkg")")
+    done
+    local choices
+    # _checklist swallows whiptail's cancel (Esc) exit code
+    # via `|| true`, so a cancelled dialog looks like an empty
+    # selection here; an empty result means "nothing to install".
+    choices=$(_checklist "$title" "$prompt" \
+        $TUI_ALTO $TUI_ANCHO $TUI_ALTO_LISTA "${items[@]}")
+    choices=$(echo "$choices" | tr -d '"')
+    echo "$choices"
+}
+
 # Install a package with confirmation prompt.
 # Handles set -e: failures are caught and reported, not fatal.
 _install_pkg() {