Only run xcompmgr if openbox is running

usr/lib/raspi-config/cmstart.sh

@@ -1,4 +1,6 @@
 #!/bin/sh
 if grep -q okay /proc/device-tree/soc/v3d@7ec00000/status 2> /dev/null || grep -q okay /proc/device-tree/soc/firmwarekms@7e600000/status 2> /dev/null ; then
-    exec xcompmgr -aR
+    if ps ax | grep -v grep | grep -q openbox ; then
+        exec xcompmgr -aR
+    fi
 fi