--- a/ApplicationModel.st	Wed Nov 18 13:10:31 2015 +0100
+++ b/ApplicationModel.st	Sat Nov 21 00:21:14 2015 +0100
@@ -1,5 +1,3 @@
-"{ Encoding: utf8 }"
-
 "
  COPYRIGHT (c) 1995 by Claus Gittinger
 	      All Rights Reserved
@@ -2754,7 +2752,10 @@
 
 initializeScreenDevice
     Screen notNil ifTrue:[
-	device := Screen current.
+        device := Screen current.
+        device isOpen ifFalse:[
+            self error:'screen device is not open'
+        ].    
     ]
 !