--- a/DeviceGraphicsContext.st	Mon Jul 27 20:05:53 1998 +0200
+++ b/DeviceGraphicsContext.st	Mon Jul 27 20:07:58 1998 +0200
@@ -2028,6 +2028,10 @@
     pY := y rounded.
 
     deviceForm := aForm asFormOn:device.
+    deviceForm isNil ifTrue:[
+        'DeviceGraphicsContext [warning]: cannot create device-form' errorPrintCR.
+        ^self
+    ].
     id := deviceForm id.
 
     id isNil ifTrue:[
@@ -2051,9 +2055,13 @@
                 'DEVGC: alpha channel not yet supported' errorPrintCR.
             ] ifTrue:[
                 deviceMask := mask asFormOn:device.
+                deviceMask isNil ifTrue:[
+                    'DeviceGraphicsContext [warning]: cannot create device-mask' errorPrintCR.
+                    ^self
+                ].
                 maskId := deviceMask id.
                 maskId notNil ifTrue:[
-		    deviceMask gcId isNil ifTrue:[deviceMask initGC].
+                    deviceMask gcId isNil ifTrue:[deviceMask initGC].
                     allColor := Color allColor.
                     allBits := allColor colorId.
 
@@ -2099,6 +2107,10 @@
                          create temp-form;
                         "
                         tmpForm := Form width:w height:h depth:device depth on:device.
+                        tmpForm isNil ifTrue:[
+                            'DeviceGraphicsContext [warning]: cannot create temp form' errorPrintCR.
+                            ^self
+                        ].
                         tmpForm initGC.
                         tmpId := tmpForm id.
                         tmpGCId := tmpForm gcId.
@@ -2356,6 +2368,10 @@
      create temp-form;
     "
     tmpForm := Form width:w height:h depth:device depth on:device.
+    tmpForm isNil ifTrue:[
+        'DeviceGraphicsContext [warning]: cannot create temp form' errorPrintCR.
+        ^self
+    ].
     "
      fill tempform
     "
@@ -2415,7 +2431,7 @@
     background := nil.
     device setFunction:function in:gcId.
 
-    "Modified: 22.4.1997 / 21:48:27 / cg"
+    "Modified: / 27.7.1998 / 20:07:22 / cg"
 !
 
 displayDeviceLineFromX:x0 y:y0 toX:x1 y:y1
@@ -3777,6 +3793,6 @@
 !DeviceGraphicsContext class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview/DeviceGraphicsContext.st,v 1.57 1998-02-21 16:30:18 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview/DeviceGraphicsContext.st,v 1.58 1998-07-27 18:07:58 cg Exp $'
 ! !
 DeviceGraphicsContext initialize!