diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08c3b0e4..1da86138 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,7 @@ Project website: https://github.com/mviereck/x11docker
 
 ## [Unreleased]
 ### Added
- - `--backend=proot`: Experimental support.
+ - `--backend=proot`: Use a rootfs on host with `proot` instead of a container.
    [(#224)](https://github.com/mviereck/x11docker/issues/224)
  - `--backend=host`: Run application from host. Replaces `-e, --exe`.
 ### Changed
diff --git a/TODO.md b/TODO.md
index 45f09e81..346d76e5 100644
--- a/TODO.md
+++ b/TODO.md
@@ -2,11 +2,15 @@
 x11docker ToDo notes
 
 ## Work in progress
+ - --backend=systemd-nspawn
  - check empty XDG_RUNTIME_DIR e.g. with --user, --hostuser
  - --xc=backend for proot and host backends
  - --backend=proot
    - --name
    - --init except systemd possible?
+   - share: ro not possible
+   - clean /tmp
+   - do old binds disappear?
    
  - kata: add new runtime for nerdctl io.containerd.kata.v2
    
diff --git a/x11docker b/x11docker
index ce7e80ba..a843fd58 100755
--- a/x11docker
+++ b/x11docker
@@ -11,7 +11,7 @@
 # Run 'x11docker --help' or scroll down to read usage information.
 # More documentation at:  https://github.com/mviereck/x11docker
 
-Version="7.1.0-beta-3"
+Version="7.1.0-beta-4"
 
 # --enforce-i: Enforce running in interactive mode to allow commands tty and weston-launch in special setups.
 grep -q -- "--enforce-i" <<< "$*" && case $- in
@@ -630,6 +630,19 @@ finish() {                      # trap EXIT routine to clean up background proce
         $($Backendbin rm -f "$Containername" 2>&1)"
       }
     ;;
+    chroot)
+      while read -r Line; do
+        debugnote "--backend=$Backend: umount $Line"
+        Source="$(cut -d'|' -f1 <<< "$Line")"
+        Target="$(cut -d'|' -f2 <<< "$Line")"
+        [ -d "$Source" ] && {
+          umount -f "$Target" || warning "umount failed on '$Target'"
+        }
+        [ -S "$Source" ] && rm "$Target"
+        [ -f "$Source" ] && rm "$Target"
+      done <<< "$Chrootmountlist"
+      #umount -t devpts "$Rootfs/dev/pts" || error "--backend=$Backend: umount of devpts failed."
+    ;;
   esac
   
   # Stop watching for messages, check others again
@@ -2301,17 +2314,29 @@ check_newxenv()  {              # find free display
   echo "$Newdisplaynumber" >> "$Numbersinusefile"
 
   # X over IP/TCP
-  [ "$Xoverip" ] || case $Xserver in
-    --xwin|--runx) 
-      Xoverip="yes" 
-      [ "$Network" = "none" ] && {
-        note "Option $Xserver needs network access.
+  [ "$Xoverip" ] || {
+    case $Mobyvm in
+      yes) 
+        Xoverip="yes" 
+      ;;
+    esac
+    case $Xserver in
+      --xwin|--runx) 
+        Xoverip="yes" 
+        [ "$Network" = "none" ] && {
+          note "Option $Xserver needs network access.
   Enabling option -I, --network."
-        check_fallback
-        Network=""
-      }
-    ;;
-  esac
+          check_fallback
+          Network=""
+        }
+      ;;
+    esac
+    case $Backend in
+      chroot)
+        Xoverip="yes"
+      ;;
+    esac
+  }
   
   # set $Newdisplay (DISPLAY of container) and $Newxsocket
   case $Xserver in
@@ -3000,16 +3025,6 @@ check_xserver() {               # check chosen X server, auto-choose X server
         esac
       ;;
     esac
-    case $Backend in
-      chroot)
-        Xoverip="yes"
-      ;;
-    esac
-    case $Mobyvm in
-      yes) 
-        Xoverip="yes" 
-      ;;
-    esac
     [ "$Xoverip" = "yes" ] && [ "$Autochooseserver" = "no" ] && debugnote "Enabled X over TCP instead of sharing unix socket."
   }
 
@@ -4746,6 +4761,7 @@ create_backendcommand() {       ### create command to run docker
 /proc|$Rootfs/proc
 /dev|$Rootfs/dev
 /run/shm|$Rootfs/run/shm"
+      Chrootmountlist=""
     ;;
   esac
   
@@ -7799,9 +7815,12 @@ Fallback: using command '$Containercommand' and enabling option --interactive."
       Sudouser="no"
       Sharewebcam=""
     ;;
-    chrootXXX) ### FIXME
+    *) 
+      error "Option --backend=$Backend: Backend $Backend is not supported."
+    ;;
+    chroot) ### FIXME
       warning "--backend=$Backend is highly experimental.
-   Rather use another backend. Even 'proot' is more stable.
+   Prefer to use another backend. Even 'proot' is more reliable.
    Isolation is close to not existant."
       [ -z "$Rootfs" ] && [ -d "$Hosthomebasefolder/ROOTFS/$Imagebasename" ] && Rootfs="$Hosthomebasefolder/ROOTFS/$Imagebasename"
       [ -z "$Rootfs" ] && error "--backend=$Backend: Did not find a rootfs for $Imagename
@@ -7817,9 +7836,6 @@ Fallback: using command '$Containercommand' and enabling option --interactive."
       }
       Switchcontaineruser="yes"
     ;;
-    *) 
-      error "Option --backend=$Backend: Backend $Backend is not supported."
-    ;;
   esac
   
   # --no-setup
@@ -9780,7 +9796,6 @@ $(nl -ba <$Cmdrc)"
           Target="$(cut -d'|' -f2 <<< "$Line")"
           [ -d "$Source" ] && {
             mkdir -v -p "$Target"
-            umount -f "$Target" || debugnote "umount failed on '$Target'"
             mount --bind "$Source" "$Target" 2>> "$Containerlogfile" || error "--backend=$Backend: mount failed.
   Last lines of log:
 $(tail "$Containerlogfile")"
@@ -9788,7 +9803,7 @@ $(tail "$Containerlogfile")"
           [ -S "$Source" ] && ln "$Source" "$Target"
           [ -f "$Source" ] && ln "$Source" "$Target"
         done <<< "$Chrootmountlist"
-        mount -t devpts devpts "$Rootfs/dev/pts" || error "--backend=$Backend: mount of devpts failed."
+#        mount -t devpts devpts "$Rootfs/dev/pts" || error "--backend=$Backend: mount of devpts failed."
       ;;
     esac