vpn configuration menu style

src/freedombone-app-vpn

     read_config_param VPN_TLS_PORT
     while true
     do
-        data=$(mktemp 2>/dev/null)
-        dialog --backtitle $"Freedombone Control Panel" \
-               --title $"VPN Configuration" \
-               --radiolist $"Choose an operation:" 13 70 3 \
-               1 $"Change TLS port (currently $VPN_TLS_PORT)" off \
-               2 $"Regenerate keys for a user" off \
-               3 $"Exit" on 2> "$data"
-        sel=$?
-        case $sel in
-            1) rm -f "$data"
-               return;;
-            255) rm -f "$data"
-                 return;;
-        esac
-        case $(cat "$data") in
+        W=(1 $"Change TLS port (currently $VPN_TLS_PORT)"
+           2 $"Regenerate keys for a user")
+
+        # shellcheck disable=SC2068
+        selection=$(dialog --backtitle $"Freedombone Administrator Control Panel" --title $"VPN" --menu $"Choose an operation, or ESC to exit:" 10 60 2 "${W[@]}" 3>&2 2>&1 1>&3)
+
+        if [ ! "$selection" ]; then
+            break
+        fi
+
+        case $selection in
             1) vpn_change_tls_port;;
             2) vpn_regenerate_client_keys;;
-            3) rm -f "$data"
-               break;;
         esac
-        rm -f "$data"
     done
 }