--- a/WindowBuilder.st	Tue May 27 11:13:44 1997 +0200
+++ b/WindowBuilder.st	Tue May 27 11:14:42 1997 +0200
@@ -186,29 +186,34 @@
 !
 
 subCanvasAt:majorKey at:minorKey
-    |majorDict spec cls k|
+    "get the subCanvas specification from major and minor key
+    "
+    |spec cls dict dkey|
 
-    k := majorKey ? #NoMajorKey.
     subCanvasSpecs notNil ifTrue:[
-        majorDict := subCanvasSpecs at:k ifAbsent:nil.
-        majorDict notNil ifTrue:[
-            spec := majorDict at:minorKey ifAbsent:nil.
+        dkey := majorKey ? #NoMajorKey.
+        dict := subCanvasSpecs at:dkey ifAbsent:nil.
+
+        dict notNil ifTrue:[
+            spec := dict at:minorKey ifAbsent:nil.
             spec notNil ifTrue:[^ spec].
         ].
     ].
+
     majorKey isNil ifTrue:[
-        "/ I provide the spec
-        application isNil ifTrue:[
-            ^ nil
-        ].
-        spec := application specificationFor:minorKey
+        spec := self safelyPerform:#specificationFor: with:minorKey.
+
+        spec isNil ifTrue:[
+            spec := self safelyPerform:minorKey
+        ]
     ] ifFalse:[
         cls := Smalltalk at:majorKey ifAbsent:nil.
-        cls notNil ifTrue:[
+        (cls notNil and:[cls respondsTo:minorKey]) ifTrue:[
             spec := cls perform:minorKey
         ]
     ].
-    ^ spec
+  ^ spec
+
 !
 
 subCanvasAt:majorKey at:minorKey put:aSpec
@@ -290,6 +295,48 @@
     focusSequence add:aComponent
 ! !
 
+!WindowBuilder methodsFor:'message sending'!
+
+safelyPerform:aSelector
+    "send the message aSelector to the receiver self or application;
+     the result returned from the send or nil is returned
+    "
+    |res|
+
+    (self respondsTo:aSelector) ifTrue:[
+        res := self perform:aSelector.
+        res notNil ifTrue:[
+            ^ res
+        ]
+    ].
+    application notNil ifTrue:[
+        (application respondsTo:aSelector) ifTrue:[
+            res := application perform:aSelector.
+        ]
+    ].
+  ^ res
+!
+
+safelyPerform:aSelector with:anArgument
+    "send the one-arg-message aSelector to the receiver self or application;
+     the result returned from the send or nil is returned
+    "
+    |res|
+
+    (self respondsTo:aSelector) ifTrue:[
+        res := self perform:aSelector with:anArgument.
+        res notNil ifTrue:[
+            ^ res
+        ]
+    ].
+    application notNil ifTrue:[
+        (application respondsTo:aSelector) ifTrue:[
+            res := application perform:aSelector with:anArgument.
+        ]
+    ].
+  ^ res
+! !
+
 !WindowBuilder methodsFor:'spec creation aspect fetch'!
 
 actionFor:aKey
@@ -612,5 +659,5 @@
 !WindowBuilder class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview2/WindowBuilder.st,v 1.34 1997-05-20 07:06:17 ca Exp $'
+    ^ '$Header: /cvs/stx/stx/libview2/WindowBuilder.st,v 1.35 1997-05-27 09:14:42 ca Exp $'
 ! !