--- a/EditTextView.st	Fri Aug 12 06:45:24 2016 +0200
+++ b/EditTextView.st	Mon Aug 15 17:31:44 2016 +0100
@@ -6415,6 +6415,36 @@
         and:t2 label:'Clipboard'
 !
 
+compareWithFile
+    "compare the selection or the whole text against the contents of a file"
+
+    |fn t1 t2|
+
+    fn := Dialog requestFileName:'Compare against file:' default:defaultFileNameForFileDialog.
+    fn isEmptyOrNil ifTrue:[^ self].
+
+    t2 := fn asFilename contentsOfEntireFile.
+    t2 isEmptyOrNil ifTrue:[
+        Dialog information:'File is empty.'.
+        ^ self.
+    ].
+
+    self hasSelection ifTrue:[
+        t1 := self selectionAsString.
+    ] ifFalse:[
+        t1 := self contents asString
+    ].
+    t1 := t1 string.
+
+    t1 = t2 ifTrue:[
+        Dialog information:'Same contents.'.
+        ^ self.
+    ].
+    DiffTextView
+        openOn:t1 label:'Editor'
+        and:t2 label:'File'
+!
+
 copySelection
     "copy contents into smalltalk copybuffer.
      Redefined to move the (currently hidden cursor) to the selection's end"
@@ -6608,6 +6638,7 @@
                     ('Builtin Spell Check'         internalSpellingSuggestion   )
                     ('Translate'                   babelFishTranslate         )
                     ('Compare with Clipboard...'   compareWithClipboard       )
+                    ('Compare with File...'        compareWithFile            )
               ).
 
     Smalltalk isStandAloneApp ifFalse:[

--- a/SelectionInListView.st	Fri Aug 12 06:45:24 2016 +0200
+++ b/SelectionInListView.st	Mon Aug 15 17:31:44 2016 +0100
@@ -1,3 +1,5 @@
+"{ Encoding: utf8 }"
+
 "
  COPYRIGHT (c) 1989 by Claus Gittinger
 	      All Rights Reserved
@@ -2219,6 +2221,8 @@
 !
 
 invalidateSelection
+    "invalidate (force async redraw) the current selection"
+
     shown ifTrue:[
         self selectionDo:[:lineNr| self invalidateLine:lineNr ].
     ].