--- a/WindowingTransformation.st	Sat Mar 22 10:26:53 2014 +0100
+++ b/WindowingTransformation.st	Mon Mar 24 20:18:28 2014 +0100
@@ -515,18 +515,16 @@
 !
 
 transformPoint:p 
-    "Apply the receiver to a point.
-     This is destructive in that the point is being modified,
-     not a copy."
+    "Apply the receiver to a point."
 
     scale isNil ifTrue:[
-	translation isNil ifTrue:[
-	    ^ p
-	].
-	^ p + translation
+        translation isNil ifTrue:[
+            ^ p
+        ].
+        ^ p + translation
     ].
     translation isNil ifTrue:[
-	^ p * scale
+        ^ p * scale
     ].
     ^ (p * scale + translation)
 ! !
@@ -580,6 +578,14 @@
 
 !WindowingTransformation methodsFor:'testing'!
 
+isIdentityTransformation
+    "return true if this is an identity transformation;
+     return false, otherwise."
+
+    ^ (scale isNil or:[scale x = 1 and:[scale y = 1]])
+        and:[translation isNil or:[translation x = 0 and:[translation y = 0]]]
+!
+
 noScale
     "return true if the identity scale is in effect;
      return false, otherwise."
@@ -667,5 +673,6 @@
 !WindowingTransformation class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview/WindowingTransformation.st,v 1.23 2011-09-29 11:18:16 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview/WindowingTransformation.st,v 1.24 2014-03-24 19:18:28 stefan Exp $'
 ! !
+