diff --git a/camino/CHAutoCompleteTextField.h b/camino/CHAutoCompleteTextField.h
index 1a3dd60333af..847b86d16a71 100644
--- a/camino/CHAutoCompleteTextField.h
+++ b/camino/CHAutoCompleteTextField.h
@@ -85,6 +85,7 @@
 - (void) onRowClicked:(NSNotification *)aNote;
 - (void) onBlur:(NSNotification *)aNote;
 - (void) onResize:(NSNotification *)aNote;
+- (void) onUndoOrRedo:(NSNotification *)aNote;
 
 - (void) setStringUndoably:(NSString*)aString fromLocation:(unsigned int)aLocation;
 - (id) fieldEditor;
diff --git a/camino/CHAutoCompleteTextField.mm b/camino/CHAutoCompleteTextField.mm
index 39c2cf61981c..9fd20c4a4c43 100644
--- a/camino/CHAutoCompleteTextField.mm
+++ b/camino/CHAutoCompleteTextField.mm
@@ -91,7 +91,8 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   mListener = (nsIAutoCompleteListener *)new AutoCompleteListener(self);
   NS_IF_ADDREF(mListener);
 
-  [self setDelegate: self]; 
+  [self setFont:[NSFont controlContentFontOfSize:0]];
+  [self setDelegate: self];
 
   // XXX the owner of the textfield should set this
   [self setSession:@"history"];
@@ -151,6 +152,14 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onResize:)
                                         name:NSWindowDidResizeNotification object:nil];
 
+  // listen for Undo/Redo to make sure autocomplete doesn't get horked.
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidRedoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidUndoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  
   // read the user default on if we should auto-complete the text field as the user
   // types or make them pick something from a list (a-la mozilla).
 	mCompleteWhileTyping = [[NSUserDefaults standardUserDefaults] boolForKey:USER_DEFAULTS_AUTOCOMPLETE_WHILE_TYPING];
@@ -501,6 +510,11 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [self resizePopup];
 }
 
+- (void) onUndoOrRedo:(NSNotification *)aNote
+{
+  [self clearResults];
+}
+
 // NSTextField delegate //////////////////////////////////
 - (void)controlTextDidChange:(NSNotification *)aNote
 {
diff --git a/camino/src/browser/AutoCompleteTextField.h b/camino/src/browser/AutoCompleteTextField.h
index 1a3dd60333af..847b86d16a71 100644
--- a/camino/src/browser/AutoCompleteTextField.h
+++ b/camino/src/browser/AutoCompleteTextField.h
@@ -85,6 +85,7 @@
 - (void) onRowClicked:(NSNotification *)aNote;
 - (void) onBlur:(NSNotification *)aNote;
 - (void) onResize:(NSNotification *)aNote;
+- (void) onUndoOrRedo:(NSNotification *)aNote;
 
 - (void) setStringUndoably:(NSString*)aString fromLocation:(unsigned int)aLocation;
 - (id) fieldEditor;
diff --git a/camino/src/browser/AutoCompleteTextField.mm b/camino/src/browser/AutoCompleteTextField.mm
index 39c2cf61981c..9fd20c4a4c43 100644
--- a/camino/src/browser/AutoCompleteTextField.mm
+++ b/camino/src/browser/AutoCompleteTextField.mm
@@ -91,7 +91,8 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   mListener = (nsIAutoCompleteListener *)new AutoCompleteListener(self);
   NS_IF_ADDREF(mListener);
 
-  [self setDelegate: self]; 
+  [self setFont:[NSFont controlContentFontOfSize:0]];
+  [self setDelegate: self];
 
   // XXX the owner of the textfield should set this
   [self setSession:@"history"];
@@ -151,6 +152,14 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onResize:)
                                         name:NSWindowDidResizeNotification object:nil];
 
+  // listen for Undo/Redo to make sure autocomplete doesn't get horked.
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidRedoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidUndoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  
   // read the user default on if we should auto-complete the text field as the user
   // types or make them pick something from a list (a-la mozilla).
 	mCompleteWhileTyping = [[NSUserDefaults standardUserDefaults] boolForKey:USER_DEFAULTS_AUTOCOMPLETE_WHILE_TYPING];
@@ -501,6 +510,11 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [self resizePopup];
 }
 
+- (void) onUndoOrRedo:(NSNotification *)aNote
+{
+  [self clearResults];
+}
+
 // NSTextField delegate //////////////////////////////////
 - (void)controlTextDidChange:(NSNotification *)aNote
 {
diff --git a/chimera/CHAutoCompleteTextField.h b/chimera/CHAutoCompleteTextField.h
index 1a3dd60333af..847b86d16a71 100644
--- a/chimera/CHAutoCompleteTextField.h
+++ b/chimera/CHAutoCompleteTextField.h
@@ -85,6 +85,7 @@
 - (void) onRowClicked:(NSNotification *)aNote;
 - (void) onBlur:(NSNotification *)aNote;
 - (void) onResize:(NSNotification *)aNote;
+- (void) onUndoOrRedo:(NSNotification *)aNote;
 
 - (void) setStringUndoably:(NSString*)aString fromLocation:(unsigned int)aLocation;
 - (id) fieldEditor;
diff --git a/chimera/CHAutoCompleteTextField.mm b/chimera/CHAutoCompleteTextField.mm
index 39c2cf61981c..9fd20c4a4c43 100644
--- a/chimera/CHAutoCompleteTextField.mm
+++ b/chimera/CHAutoCompleteTextField.mm
@@ -91,7 +91,8 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   mListener = (nsIAutoCompleteListener *)new AutoCompleteListener(self);
   NS_IF_ADDREF(mListener);
 
-  [self setDelegate: self]; 
+  [self setFont:[NSFont controlContentFontOfSize:0]];
+  [self setDelegate: self];
 
   // XXX the owner of the textfield should set this
   [self setSession:@"history"];
@@ -151,6 +152,14 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onResize:)
                                         name:NSWindowDidResizeNotification object:nil];
 
+  // listen for Undo/Redo to make sure autocomplete doesn't get horked.
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidRedoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidUndoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  
   // read the user default on if we should auto-complete the text field as the user
   // types or make them pick something from a list (a-la mozilla).
 	mCompleteWhileTyping = [[NSUserDefaults standardUserDefaults] boolForKey:USER_DEFAULTS_AUTOCOMPLETE_WHILE_TYPING];
@@ -501,6 +510,11 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [self resizePopup];
 }
 
+- (void) onUndoOrRedo:(NSNotification *)aNote
+{
+  [self clearResults];
+}
+
 // NSTextField delegate //////////////////////////////////
 - (void)controlTextDidChange:(NSNotification *)aNote
 {
diff --git a/chimera/src/browser/AutoCompleteTextField.h b/chimera/src/browser/AutoCompleteTextField.h
index 1a3dd60333af..847b86d16a71 100644
--- a/chimera/src/browser/AutoCompleteTextField.h
+++ b/chimera/src/browser/AutoCompleteTextField.h
@@ -85,6 +85,7 @@
 - (void) onRowClicked:(NSNotification *)aNote;
 - (void) onBlur:(NSNotification *)aNote;
 - (void) onResize:(NSNotification *)aNote;
+- (void) onUndoOrRedo:(NSNotification *)aNote;
 
 - (void) setStringUndoably:(NSString*)aString fromLocation:(unsigned int)aLocation;
 - (id) fieldEditor;
diff --git a/chimera/src/browser/AutoCompleteTextField.mm b/chimera/src/browser/AutoCompleteTextField.mm
index 39c2cf61981c..9fd20c4a4c43 100644
--- a/chimera/src/browser/AutoCompleteTextField.mm
+++ b/chimera/src/browser/AutoCompleteTextField.mm
@@ -91,7 +91,8 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   mListener = (nsIAutoCompleteListener *)new AutoCompleteListener(self);
   NS_IF_ADDREF(mListener);
 
-  [self setDelegate: self]; 
+  [self setFont:[NSFont controlContentFontOfSize:0]];
+  [self setDelegate: self];
 
   // XXX the owner of the textfield should set this
   [self setSession:@"history"];
@@ -151,6 +152,14 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onResize:)
                                         name:NSWindowDidResizeNotification object:nil];
 
+  // listen for Undo/Redo to make sure autocomplete doesn't get horked.
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidRedoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onUndoOrRedo:)
+                                               name:NSUndoManagerDidUndoChangeNotification
+                                             object:[[self fieldEditor] undoManager]];
+  
   // read the user default on if we should auto-complete the text field as the user
   // types or make them pick something from a list (a-la mozilla).
 	mCompleteWhileTyping = [[NSUserDefaults standardUserDefaults] boolForKey:USER_DEFAULTS_AUTOCOMPLETE_WHILE_TYPING];
@@ -501,6 +510,11 @@ NS_IMPL_ISUPPORTS1(AutoCompleteListener, nsIAutoCompleteListener)
   [self resizePopup];
 }
 
+- (void) onUndoOrRedo:(NSNotification *)aNote
+{
+  [self clearResults];
+}
+
 // NSTextField delegate //////////////////////////////////
 - (void)controlTextDidChange:(NSNotification *)aNote
 {