--- a/ChangesBrowser.st	Thu Dec 11 22:49:15 2014 +0100
+++ b/ChangesBrowser.st	Thu Dec 11 22:56:28 2014 +0100
@@ -733,6 +733,7 @@
          (MenuItem
             activeHelpKey: deleteAllForClass
             enabled: hasSelectionHolder
+            isVisible: canDeleteChanges
             label: 'Delete all for Class'
             itemValue: doDeleteClassAll
             translateLabel: true
@@ -742,6 +743,7 @@
          (MenuItem
             activeHelpKey: deleteForClassToEnd
             enabled: hasSelectionHolder
+            isVisible: canDeleteChanges
             label: 'Delete for Class to End'
             itemValue: doDeleteClassRest
             translateLabel: true
@@ -852,6 +854,12 @@
     ^ autoloadAsRequired
 !
 
+canDeleteChanges
+    "makes the delete buttons in the toolbar visible"
+
+    ^ true.
+!
+
 changeListSelectionHolder
     changeListSelectionHolder isNil ifTrue:[
         changeListSelectionHolder := nil asValue.
@@ -4596,8 +4604,7 @@
      Return the result of the compare (same -> true, different -> false, uncomparable -> nil).
      If doShowResult is true, the outcome is shown in a dialog/diffViewer."
 
-    |aStream chunk sawExcla parseTree thisClass cat oldSource newSource
-     parser sel oldMethod outcome showDiff d t1 t2 selector isLoaded beep superClass thisClassSym varsHere varsInChange addedVars removedVars
+    |aStream chunk sawExcla parseTree thisClass cat oldSource newSource outcome showDiff d selector isLoaded beep superClass thisClassSym varsHere varsInChange addedVars removedVars
      isSame ownerClass superClassHere superClassInChange sameAndOutcome|
 
     aStream := self streamForChange:changeNr.
@@ -4745,10 +4752,12 @@
             ]
         ]
     ] ifTrue:[
-        Class nameSpaceQuerySignal answer:(self nameSpaceForApply)
-        do:[
-            parseTree := self parseExpression:chunk.
-        ].
+        Class nameSpaceQuerySignal 
+            answer:(self nameSpaceForApply)
+            do:[
+                parseTree := self parseExpression:chunk.
+            ].
+
         (parseTree notNil
          and:[parseTree ~~ #Error
          and:[parseTree isMessage]]) ifTrue:[
@@ -4790,11 +4799,6 @@
                 ].
 
                 thisClass isBehavior ifTrue:[
-                    (isLoaded := self checkClassIsLoaded:thisClass) ifFalse:[
-                        outcome := 'Cannot compare this change\\(compare requires class to be loaded).'.
-                        isSame := nil.
-                    ].
-
                     parseTree selector == #methodsFor ifTrue:[
                         cat := 'Dolphin methods'.
                     ] ifFalse:[
@@ -4806,69 +4810,21 @@
                     ].
                     newSource := aStream nextChunk.
 
-                    Class nameSpaceQuerySignal answer:(self nameSpaceForApply)
-                    do:[
-                        parser := Parser parseMethod:newSource in:thisClass.
+                    isSame := self 
+                                compareMethodSource:newSource 
+                                withVersionInClass:thisClass 
+                                into:[:outcomeResult :beepResult :oldSourceResult| 
+                                    outcome := outcomeResult.
+                                    beep := beepResult.
+                                    oldSource := oldSourceResult.
+                                ].
+
+                    isSame isNil ifTrue:[
+                        showDiff := false.
+                    ] ifFalse:[
+                        showDiff := isSame not.
                     ].
-                    (parser notNil and:[parser ~~ #Error]) ifTrue:[
-                        sel := parser selector.
-                        oldMethod := thisClass compiledMethodAt:sel.
-                        oldMethod notNil ifTrue:[
-                            (oldMethod category = cat) ifFalse:[
-"/                                Transcript showCR:'category changed.'.
-                            ].
-                            oldSource := oldMethod source.
-                            (oldSource = newSource) ifTrue:[
-                                outcome := 'Same source'.
-                                isSame := true.
-                            ] ifFalse:[
-                                oldSource isNil ifTrue:[
-                                    beep := true.
-                                    outcome := 'No source for compare.'.
-                                    isSame := true.
-                                ] ifFalse:[
-                                    "/
-                                    "/ compare for tabulator <-> space changes
-                                    "/ before showing diff ...
-                                    "/
-                                    t1 := oldSource asCollectionOfLines collect:[:s | s withTabsExpanded].
-                                    t2 := newSource asCollectionOfLines collect:[:s | s withTabsExpanded].
-                                    t1 = t2 ifTrue:[
-                                        outcome := 'Same source'.
-                                        isSame := true.
-                                    ] ifFalse:[
-                                        outcome := 'Source changed.'.
-                                        showDiff := true.
-                                        isSame := false.
-
-                                        "/
-                                        "/ check if only historyLine diffs
-                                        "/
-                                        (HistoryManager notNil
-                                        and:[HistoryManager isActive]) ifTrue:[
-                                            (HistoryManager withoutHistoryLines:newSource)
-                                            =
-                                            (HistoryManager withoutHistoryLines:oldSource)
-                                            ifTrue:[
-                                                outcome := 'Same source (history only)'.
-                                                isSame := true.
-                                                showDiff := false.
-                                            ]
-                                        ].
-                                    ]
-                                ]
-                            ]
-                        ] ifFalse:[
-                            isLoaded ifTrue:[
-                                beep := true.
-                                outcome := 'Method does not exist.'.
-                                isSame := nil.
-                            ]
-                        ]
-                    ] ifFalse:[
-                        outcome := 'Change is unparsable (parse error).'.
-                        isSame := nil.
-                    ].
+
                     doShowResult ifTrue:[
                         (showDiff and:[oldSource notNil and:[newSource notNil]]) ifTrue:[
                             d := DiffCodeView
@@ -4956,6 +4912,78 @@
     ^ nil -> 'Unhandled receiver'
 !
 
+compareMethodSource:newSource withVersionInClass:thisClass into:aThreeArgBlock
+    "returns true/false/nil if same,different,undecided;
+     also provides a message and a beep-boolean via the passed in block"
+
+    |parser sel oldMethod oldSource outcome t1 t2 isLoaded|
+
+    Class nameSpaceQuerySignal answer:(self nameSpaceForApply)
+    do:[
+        parser := Parser parseMethod:newSource in:thisClass.
+    ].
+    (parser isNil or:[parser == #Error]) ifTrue:[
+        outcome := 'Change is unparsable (parse error).'.
+        aThreeArgBlock value:outcome value:true "beep" value:nil.
+        ^ nil.
+    ].
+
+    sel := parser selector.
+    oldMethod := thisClass compiledMethodAt:sel.
+    oldMethod isNil ifTrue:[
+        (isLoaded := self checkClassIsLoaded:thisClass) ifFalse:[
+            outcome := 'Cannot compare this change\\(compare requires class to be loaded).'.
+        ] ifTrue:[
+            outcome := 'Method does not exist.'.
+        ].
+        aThreeArgBlock value:outcome value:true "beep" value:nil.
+        ^ nil.
+    ].
+
+    oldSource := oldMethod source.
+    oldSource isNil ifTrue:[
+        outcome := 'No source for compare.'.
+        aThreeArgBlock value:outcome value:true "beep" value:nil.
+        ^ nil.
+    ].
+    (oldSource = newSource) ifTrue:[
+        outcome := 'Same source'.
+        aThreeArgBlock value:outcome value:false "beep" value:oldSource.
+        ^ true.
+    ].
+
+    "/
+    "/ compare for tabulator <-> space changes
+    "/ before showing diff ...
+    "/
+    t1 := oldSource asCollectionOfLines collect:[:s | s withTabsExpanded].
+    t2 := newSource asCollectionOfLines collect:[:s | s withTabsExpanded].
+    t1 = t2 ifTrue:[
+        outcome := 'Same source'.
+        aThreeArgBlock value:outcome value:false "beep" value:oldSource.
+        ^ true.
+    ].
+
+    "/
+    "/ check if only historyLine diffs
+    "/
+    (HistoryManager notNil
+    and:[HistoryManager isActive]) ifTrue:[
+        (HistoryManager withoutHistoryLines:newSource)
+        =
+        (HistoryManager withoutHistoryLines:oldSource)
+        ifTrue:[
+            outcome := 'Same source (history only)'.
+            aThreeArgBlock value:outcome value:false "beep" value:oldSource.
+            ^ true.
+        ]
+    ].
+
+    outcome := 'Source changed.'.
+    aThreeArgBlock value:outcome value:false "beep" value:oldSource.
+    ^ false.
+!
+
 comparePackageChange:parseTree
     |receiverExpression method thisClass|
 
@@ -6498,10 +6526,10 @@
 !ChangesBrowser class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libtool/ChangesBrowser.st,v 1.462 2014-12-11 20:48:16 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/ChangesBrowser.st,v 1.463 2014-12-11 21:56:28 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libtool/ChangesBrowser.st,v 1.462 2014-12-11 20:48:16 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/ChangesBrowser.st,v 1.463 2014-12-11 21:56:28 cg Exp $'
 ! !