--- a/DeviceGraphicsContext.st	Mon Sep 11 16:21:13 2017 +0200
+++ b/DeviceGraphicsContext.st	Wed Sep 13 09:40:34 2017 +0200
@@ -2519,6 +2519,10 @@
      paintClr bgPaintClr|
 
     deviceForm := aFormOrImage asFormOn:device.
+    deviceForm isNil ifTrue:[
+        Logger warning:'invalid form draw (no device form) - ignored'.
+        ^ self
+    ].
     id := deviceForm drawableId.
 
     "temporary ..."
@@ -2839,6 +2843,7 @@
     background := nil.
 
     "Modified: / 31-08-2017 / 19:35:55 / cg"
+    "Modified: / 06-09-2017 / 12:31:45 / Maren"
 !
 
 displayDeviceOpaqueString:aStringArg from:index1 to:index2 in:fontArg x:x y:y