* Headers/gnustep/base/NSUndoManager.h: Add

NSUndoCloseGroupingRunLoopOrdering enum.  Replace instance
        variables _registeredUndo with _runLoopGroupingPending and
        _actionName with _unused1.
        * Source/NSUndoManager.m: Added documentation.
        Added actionName instance variable to PrivateUndoGroup.
        (-[PrivateUndoGroup actionName]): New method.
        (-[PrivateUndoGroup setActionName]): Ditto.
        (-[PrivateUndoGroup dealloc]): Release new instance variable.
        (-[PrivateUndoGroup initWithParent:]): Initialize actionName.
        (-[NSUndoManager forwardInvocation]): Implicitly call
        beginUndoGrouping if group has not been setup and we are
        grouping by events.  Register _loop: invocation if none is already
        pending and if we are grouping by event.
        (-[NSUndoManager registerUndoWithTarget:selector:object]):
        Ditto.
        (-[NSUndoManager methodSignatureForSelector:]): Overriden to
        forward request to target supplied by
        -prepareWithInvocationTarget: if available.
        (-[NSUndoManager _loop:]): Set flag to determine pending
        _loop: processing.
        (-[NSUndoManager init]): Removed access to _actionName.  Have
        receiver default to group by event.
        (-[NSUndoManager dealloc]): Ditto.
        (-[NSUndoManager enableUndoRegistration]): Remove access to
        _registeredUndo.
        (-[NSUndoManager redo]): Simplified implementation.
        (-[NSUndoManager redoActionName:]: Retrieve action name from
        first grouping of the redo stack.
        (-[NSUndoManager redoMenuTitleForUndoActionName:]): Add
        comment about localization.
        (-[NSUndoManager undoMenuTitleForUndoActionName:]): Ditto.
        (-[NSUndoManager setActionName:]): Forward call to current
        grouping.
        (-[NSUndoManager undoActionName:]: Retrieve action name from
        first grouping of the undo stack.
        (-[NSUndoManager setRunLoopModes:]): Use correct run loop
        ordering and set flag for pending _loop: invocation.
        (-[NSUndoManager undoNestedGroup]): Removed special case
        handling of _registeredUndo.  Raise
        NSInternalInconsistencyException if grouping is still in
        progress.  Simplified implementation.


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@17221 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,46 @@
+2003-07-15  David Ayers  <d.ayers@inode.at>
+
+	* Headers/gnustep/base/NSUndoManager.h: Add
+	NSUndoCloseGroupingRunLoopOrdering enum.  Replace instance
+	variables _registeredUndo with _runLoopGroupingPending and
+	_actionName with _unused1.
+	* Source/NSUndoManager.m: Added documentation.
+	Added actionName instance variable to PrivateUndoGroup.
+	(-[PrivateUndoGroup actionName]): New method.
+	(-[PrivateUndoGroup setActionName]): Ditto.
+	(-[PrivateUndoGroup dealloc]): Release new instance variable.
+	(-[PrivateUndoGroup initWithParent:]): Initialize actionName.
+	(-[NSUndoManager forwardInvocation]): Implicitly call
+	beginUndoGrouping if group has not been setup and we are grouping
+	by events.  Register _loop: invocation if none is already pending
+	and if we are grouping by event.
+	(-[NSUndoManager registerUndoWithTarget:selector:object]): Ditto.
+	(-[NSUndoManager methodSignatureForSelector:]): Overriden to
+	forward request to target supplied by
+	-prepareWithInvocationTarget: if available.
+	(-[NSUndoManager _loop:]): Set flag to determine pending _loop:
+	processing.
+	(-[NSUndoManager init]): Removed access to _actionName.  Have
+	receiver default to group by event.
+	(-[NSUndoManager dealloc]): Ditto.
+	(-[NSUndoManager enableUndoRegistration]): Remove access to
+	_registeredUndo.
+	(-[NSUndoManager redo]): Simplified implementation.
+	(-[NSUndoManager redoActionName:]: Retrieve action name from first
+	grouping of the redo stack.
+	(-[NSUndoManager redoMenuTitleForUndoActionName:]): Add comment
+	about localization.
+	(-[NSUndoManager undoMenuTitleForUndoActionName:]): Ditto.
+	(-[NSUndoManager setActionName:]): Forward call to current
+	grouping.
+	(-[NSUndoManager undoActionName:]: Retrieve action name from first
+	grouping of the undo stack.
+	(-[NSUndoManager setRunLoopModes:]): Use correct run loop ordering
+	and set flag for pending _loop: invocation.
+	(-[NSUndoManager undoNestedGroup]): Removed special case handling
+	of _registeredUndo.  Raise NSInternalInconsistencyException if
+	grouping is still in progress.  Simplified implementation.
+
 2003-07-15  Alexander Malmberg <alexander@malmberg.org>
 
 	* Source/NSConnection.m: When creating new connection with registered

Headers/gnustep/base/NSUndoManager.h

@@ -30,6 +30,11 @@
 @class NSMutableArray;
 @class NSInvocation;
 
+/** Defines run loop ordering for closing undo groupings. */
+enum {
+  NSUndoCloseGroupingRunLoopOrdering = 350000
+};
+
 /* Public notification */
 GS_EXPORT NSString *NSUndoManagerCheckpointNotification;
 GS_EXPORT NSString *NSUndoManagerDidOpenUndoGroupNotification;
@@ -44,14 +49,14 @@ GS_EXPORT NSString *NSUndoManagerWillUndoChangeNotification;
 @private
     NSMutableArray	*_redoStack;
     NSMutableArray	*_undoStack;
-    NSString		*_actionName;
+    id                  *_unused1;
     id			_group;
     id			_nextTarget;
     NSArray		*_modes;
     BOOL		_isRedoing;
     BOOL		_isUndoing;
     BOOL		_groupsByEvent;
-    BOOL		_registeredUndo;
+    BOOL		_runLoopGroupingPending;
     unsigned		_disableCount;
     unsigned		_levelsOfUndo;
 }
@@ -73,7 +78,7 @@ GS_EXPORT NSString *NSUndoManagerWillUndoChangeNotification;
 - (void) redo;
 - (NSString*) redoActionName;
 - (NSString*) redoMenuItemTitle;
-- (NSString*) redoMenuTitleForUndoActionName: (NSString*)name;
+- (NSString*) redoMenuTitleForUndoActionName: (NSString*)actionName;
 - (void) registerUndoWithTarget: (id)target
 		       selector: (SEL)aSelector
 			 object: (id)anObject;
@@ -87,7 +92,7 @@ GS_EXPORT NSString *NSUndoManagerWillUndoChangeNotification;
 - (void) undo;
 - (NSString*) undoActionName;
 - (NSString*) undoMenuItemTitle;
-- (NSString*) undoMenuTitleForUndoActionName: (NSString*)name;
+- (NSString*) undoMenuTitleForUndoActionName: (NSString*)actionName;
 - (void) undoNestedGroup;
 
 @end

Source/NSUndoManager.m

@@ -55,16 +55,20 @@ NSString *NSUndoManagerWillUndoChangeNotification =
  */
 @interface	PrivateUndoGroup : NSObject
 {
-    PrivateUndoGroup	*parent;
-    NSMutableArray	*actions;
+  PrivateUndoGroup	*parent;
+  NSMutableArray	*actions;
+  NSString              *actionName;
 }
 - (NSMutableArray*) actions;
+
+- (NSString*) actionName;
 - (void) addInvocation: (NSInvocation*)inv;
 - (id) initWithParent: (PrivateUndoGroup*)parent;
 - (void) orphan;
 - (PrivateUndoGroup*) parent;
 - (void) perform;
 - (BOOL) removeActionsForTarget: (id)target;
+- (void) setActionName: (NSString*)name;
 @end
 
 @implementation	PrivateUndoGroup
@@ -74,6 +78,11 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   return actions;
 }
 
+- (NSString*) actionName
+{
+  return actionName;
+}
+
 - (void) addInvocation: (NSInvocation*)inv
 {
   if (actions == nil)
@@ -87,6 +96,7 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 {
   RELEASE(actions);
   RELEASE(parent);
+  RELEASE(actionName);
   [super dealloc];
 }
 
@@ -97,6 +107,7 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     {
       parent = RETAIN(p);
       actions = nil;
+      actionName = @"";
     }
   return self;
 }
@@ -147,6 +158,11 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   return NO;
 }
 
+- (void) setActionName: (NSString *)name
+{
+  ASSIGNCOPY(actionName,name);
+}
+
 @end
 
 
@@ -169,6 +185,7 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 	}
       [self beginUndoGrouping];
     }
+  _runLoopGroupingPending = NO;
 }
 @end
 
@@ -179,6 +196,13 @@ NSString *NSUndoManagerWillUndoChangeNotification =
  */
 @implementation NSUndoManager
 
+/**
+ * Starts a new grouping of undo actions which can be 
+ * atomically undone by an [-undo] invovation.
+ * This method posts an NSUndoManagerCheckpointNotification
+ * unless an undo is currently in progress.  It posts an
+ * NSUndoManagerDidOpenUndoGroupNotification upon creating the grouping.
+ */
 - (void) beginUndoGrouping
 {
   PrivateUndoGroup	*parent;
@@ -207,6 +231,10 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Returns whether the receiver can service redo requests and
+ * posts a NSUndoManagerCheckpointNotification.
+ */
 - (BOOL) canRedo
 {
   [[NSNotificationCenter defaultCenter]
@@ -222,6 +250,13 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Returns whether the receiver has any action groupings
+ * on the stack to undo.  It does not imply, that the
+ * receiver is currently in a state to service an undo
+ * request.  Make sure [-endEndGrouping] is invoked before
+ * requesting either an [-undo] or an [-undoNestedGroup].
+ */
 - (BOOL) canUndo
 {
   if ([_undoStack count] > 0)
@@ -242,23 +277,37 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 					   argument: nil];
   RELEASE(_redoStack);
   RELEASE(_undoStack);
-  RELEASE(_actionName);
   RELEASE(_group);
   RELEASE(_modes);
   [super dealloc];
 }
 
+/**
+ * Disables the registration of operations with with either
+ * [-registerUndoWithTarget:selector:object:] or
+ * [-forwardInvocation:].  This method may be called multiple
+ * times.  Each will need to be paired to a call of 
+ * [-enableUndoRegistration] before registration is actually
+ * reenabled.
+ */
 - (void) disableUndoRegistration
 {
   _disableCount++;
 }
 
+/**
+ * Matches previous calls of to [-disableUndoRegistration].  
+ * Only call this method to that end.  Once all are matched, 
+ * the registration of [-registerUndoWithTarget:selector:object:]
+ * and [-forwardInvocation:] are reenabled.  If this method is
+ * called without a matching -disableUndoRegistration,
+ * it will raise an NSInternalInconsistencyException.
+ */
 - (void) enableUndoRegistration
 {
   if (_disableCount > 0)
     {
       _disableCount--;
-      _registeredUndo = NO;	/* No operations since registration enabled. */
     }
   else
     {
@@ -267,6 +316,14 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Matches previous calls of to [-beginUndoGrouping] and 
+ * puts the group on the undo stack.  This method posts
+ * an NSUndoManagerCheckpointNotification and
+ * a NSUndoManagerWillCloseUndoGroupNotification.  
+ * If there was no matching call to -beginUndoGrouping,
+ * this method will raise an NSInternalInconsistencyException.
+ */
 - (void) endUndoGrouping
 {
   PrivateUndoGroup	*g;
@@ -319,6 +376,32 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   RELEASE(g);
 }
 
+/**
+ * Registers the invocation with the current undo grouping.
+ * This method is part of the NSInvocation-based undo registration
+ * as opposed to the simpler [-registerUndoWithTarget:selector:object:]
+ * technique. <br/>
+ * You generally never invoke this method directly.  
+ * Instead invoke [-prepareWithInvocationTarget:] with the target of the
+ * undo action and then invoke the targets method to undo the action
+ * on the return value of -prepareWithInvocationTarget:
+ * which actually is the undo manager.
+ * The runtime will then fallback to -forwardInvocation: to do the actual
+ * registration of the invocation.
+ * The invocation will added to the current grouping.<br/>
+ * If the registrations have been disabled through [-disableUndoRegistration],
+ * this method does nothing.<br/>
+ * Unless the reciever implicitly 
+ * groups operations by event, the this method must have been preceeded
+ * with a [-beginUndoGrouping] message.  Otherwise it will raise an
+ * NSInternalInconsistencyException. <br/>
+ * Unless this method is invoked as part of a [-undo] or [-undoNestedGroup]
+ * processing, the redo stack is cleared.<br/>
+ * If the reciever [-groupsByEvents] and this is the first call to this
+ * method since the last run loop processing, this method sets up
+ * the reciever to process the [-endUndoGrouping] at the
+ * end of the event loop.
+ */
 - (void) forwardInvocation: (NSInvocation*)anInvocation
 {
   if (_disableCount == 0)
@@ -330,8 +413,15 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 	}
       if (_group == nil)
 	{
-	  [NSException raise: NSInternalInconsistencyException
-		      format: @"forwardInvocation without beginUndoGrouping"];
+	  if ([self groupsByEvent])
+	    {
+	      [self beginUndoGrouping];
+	    }
+	  else
+	    {
+	      [NSException raise: NSInternalInconsistencyException
+			  format: @"forwardInvocation without beginUndoGrouping"];
+	    }
 	}
       [anInvocation setTarget: _nextTarget];
       _nextTarget = nil;
@@ -340,10 +430,45 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 	{
 	  [_redoStack removeAllObjects];
 	}
-      _registeredUndo = YES;
+      if ((_runLoopGroupingPending == NO) && ([self groupsByEvent] == YES))
+	{
+	  [[NSRunLoop currentRunLoop] performSelector: @selector(_loop:)
+				      target: self
+				      argument: nil
+				      order: NSUndoCloseGroupingRunLoopOrdering
+				      modes: _modes];
+	  _runLoopGroupingPending = YES;
+	}
     }
 }
 
+/**
+ * If the reciever was sent a [-prepareWithInvocationTarget:] and
+ * the target's method hasn't been invoked on the reciever yet, this
+ * method forwards the request to the target.
+ * Otherwise or if the target didn't return a signature, the message
+ * is sent to super.
+ */
+- (NSMethodSignature*) methodSignatureForSelector: (SEL)selector
+{
+  NSMethodSignature *sig = nil;
+
+  if (_nextTarget != nil)
+    {
+      sig = [_nextTarget methodSignatureForSelector: selector];
+    }
+  if (sig == nil)
+    {
+      sig = [super methodSignatureForSelector: selector];
+    }
+  return sig;
+}
+
+/**
+ * Returns the current number of groupings.  These are the current
+ * groupings which can be nested, not the number of of groups on either
+ * the undo or redo stack.
+ */
 - (int) groupingLevel
 {
   PrivateUndoGroup	*g = (PrivateUndoGroup*)_group;
@@ -357,6 +482,14 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   return level;
 }
 
+/**
+ * Returns whether the receiver currently groups undo
+ * operations by events.  When it does, so it implicitly 
+ * invokes [-beginUndoGrouping] upon registration of undo
+ * operations and registers an internal call to insure
+ * the invocation of [-endUndoGrouping] at the end of the 
+ * run loop.
+ */
 - (BOOL) groupsByEvent
 {
   return _groupsByEvent;
@@ -367,25 +500,34 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   self = [super init];
   if (self)
     {
-      _actionName = @"";
       _redoStack = [[NSMutableArray alloc] initWithCapacity: 16];
       _undoStack = [[NSMutableArray alloc] initWithCapacity: 16];
+      _groupsByEvent = YES;
       [self setRunLoopModes:
 	[NSArray arrayWithObjects: NSDefaultRunLoopMode, nil]];
     }
   return self;
 }
 
+/**
+ * Returns whether the receiver is currently processing a redo.
+ */
 - (BOOL) isRedoing
 {
   return _isRedoing;
 }
 
+/**
+ * Returns whether the receiver is currently processing an undo.
+ */
 - (BOOL) isUndoing
 {
   return _isUndoing;
 }
 
+/**
+ * Returns whether the receiver will currently register undo operations.
+ */
 - (BOOL) isUndoRegistrationEnabled
 {
   if (_disableCount == 0)
@@ -398,17 +540,44 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Returns the maximium number of undo groupings the reciever will maintain.
+ * The default value is 0 meaning the number is only limited by
+ * memory availability.
+ */
 - (unsigned int) levelsOfUndo
 {
   return _levelsOfUndo;
 }
 
+/**
+ * Prepares the receiver to registers an invocation-based undo operation.
+ * This method is part of the NSInvocation-based undo registration
+ * as opposed to the simpler [-registerUndoWithTarget:selector:object:]
+ * technique. <br/>
+ * You invoke this method with the target of the
+ * undo action and then invoke the targets method to undo the action
+ * on the return value of this invocation
+ * which actually is the undo manager.
+ * The runtime will then fallback to [-forwardInvocation:] to do the actual
+ * registration of the invocation.
+ */
 - (id) prepareWithInvocationTarget: (id)target
 {
   _nextTarget = target;
   return self;
 }
 
+/**
+ * Performs a redo of previous undo request by taking the top grouping
+ * from the redo stack and invoking them.  This method posts an 
+ * NSUndoManagerCheckpointNotification notification to allow the client
+ * to porcess any pending changes before proceding.  If there are groupings
+ * on the redo stack, the top object is poped of the stack and invoked
+ * within a nested [-beginUndoGrouping]/[-endUndoGrouping].  During this
+ * pocessing, the operations registered for undo are recorded on the undo
+ * stack again.<br\>
+ */
 - (void) redo
 {
   if (_isUndoing || _isRedoing)
@@ -427,54 +596,103 @@ NSString *NSUndoManagerWillUndoChangeNotification =
       [[NSNotificationCenter defaultCenter]
 	  postNotificationName: NSUndoManagerWillRedoChangeNotification
 		    object: self];
-      groupToRedo = [_redoStack objectAtIndex: [_redoStack count] - 1];
-      IF_NO_GC([groupToRedo retain]);
-      [_redoStack removeObjectAtIndex: [_redoStack count] - 1];
+
+      groupToRedo = RETAIN([_redoStack lastObject]);
+      [_redoStack removeLastObject];
+
       oldGroup = _group;
       _group = nil;
       _isRedoing = YES;
+
       [self beginUndoGrouping];
       [groupToRedo perform];
       RELEASE(groupToRedo);
       [self endUndoGrouping];
+
       _isRedoing = NO;
       _group = oldGroup;
+
       [[NSNotificationCenter defaultCenter]
 	  postNotificationName: NSUndoManagerDidRedoChangeNotification
 			object: self];
     }
 }
 
+/**
+ * If the receiver can preform a redo, this method returns
+ * the action name previously associated with the top grouping with
+ * [-setActionName:].  This name should identify the action to be redone.
+ * If there are no items on the redo stack this method returns nil.
+ * If no action name hs been set, this method returns an empty string.
+ */
 - (NSString*) redoActionName
 {
   if ([self canRedo] == NO)
     {
       return nil;
     }
-  return _actionName;
+  return [[_redoStack lastObject] actionName];
 }
 
+/**
+ * Returns the full localized title of the actions to be displayed
+ * as a menu item.  This method first invokes [-redoActionName] and 
+ * passes it to [-redoMenuTitelForUndoActionName:] and returns the result.
+ */
 - (NSString*) redoMenuItemTitle
 {
   return [self redoMenuTitleForUndoActionName: [self redoActionName]];
 }
 
-- (NSString*) redoMenuTitleForUndoActionName: (NSString*)name
+/**
+ * Returns the localized title of the actions to be displayed
+ * as a menu item identified by actionName, by appending a
+ * localized command string like @"Redo <localized(actionName)>".
+ */
+- (NSString*) redoMenuTitleForUndoActionName: (NSString*)actionName
 {
-  if (name)
+  /* 
+   * FIXME: The terms @"Redo" and @"Redo %@" should be localized.
+   * Possibly with the introduction of GSBaseLocalizedString() private
+   * the the library.
+   */
+  if (actionName)
     {
-      if ([name isEqual: @""])
+      if ([actionName isEqual: @""])
 	{
 	  return @"Redo";
 	}
       else
 	{
-	  return [NSString stringWithFormat: @"Redo %@", name];
+	  return [NSString stringWithFormat: @"Redo %@", actionName];
 	}
     }
-  return name;
+  return actionName;
 }
 
+/**
+ * Registers an undo operation.
+ * This method is the simple target-action-based undo registration
+ * as opposed to the sophisticated [-forwardInvocation:]
+ * mechanism. <br/>
+ * You invoke this method with the target of the
+ * undo action providing the selector which can perform the undo with
+ * the provided object.  The object is often a dictionary of the
+ * identifying the attribute and thier values before the change.
+ * The invocation will added to the current grouping.<br/>
+ * If the registrations have been disabled through [-disableUndoRegistration],
+ * this method does nothing.<br/>
+ * Unless the reciever implicitly 
+ * groups operations by event, the this method must have been preceeded
+ * with a [-beginUndoGrouping] message.  Otherwise it will raise an
+ * NSInternalInconsistencyException. <br/>
+ * Unless this method is invoked as part of a [-undo] or [-undoNestedGroup]
+ * processing, the redo stack is cleared.<br/>
+ * If the reciever [-groupsByEvents] and this is the first call to this
+ * method since the last run loop processing, this method sets up
+ * the reciever to process the [-endUndoGrouping] at the
+ * end of the event loop.
+ */
 - (void) registerUndoWithTarget: (id)target
 		       selector: (SEL)aSelector
 			 object: (id)anObject
@@ -487,8 +705,15 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 
       if (_group == nil)
 	{
-	  [NSException raise: NSInternalInconsistencyException
-		      format: @"registerUndo without beginUndoGrouping"];
+	  if ([self groupsByEvent])
+	    {
+	      [self beginUndoGrouping];
+	    }
+	  else
+	    {
+	      [NSException raise: NSInternalInconsistencyException
+			   format: @"registerUndo without beginUndoGrouping"];
+	    }
 	}
       g = _group;
       sig = [target methodSignatureForSelector: aSelector];
@@ -501,10 +726,26 @@ NSString *NSUndoManagerWillUndoChangeNotification =
 	{
 	  [_redoStack removeAllObjects];
 	}
-      _registeredUndo = YES;
+      if ((_runLoopGroupingPending == NO) && ([self groupsByEvent] == YES))
+	{
+	  [[NSRunLoop currentRunLoop] performSelector: @selector(_loop:)
+				      target: self
+				      argument: nil
+				      order: NSUndoCloseGroupingRunLoopOrdering
+				      modes: _modes];
+	  _runLoopGroupingPending = YES;
+	}
     }
 }
 
+/**
+ * Removes all grouping stored in the receiver.  This clears the both
+ * the undo and the redo stacks.  This method is if the sole client
+ * of the undo manager will be unable to service any undo or redo events.
+ * The client can call this method in its -dealloc method, unless the
+ * undo manager has several clients, in which case 
+ * [-removeAllActionsWithTarget:] is more apropriate.
+ */
 - (void) removeAllActions
 {
   [_redoStack removeAllObjects];
@@ -514,6 +755,13 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   _disableCount = 0;
 }
 
+/**
+ * Removes all actions recorded for the given target.  This method is
+ * is useful when a client of the undo manager will be unable to
+ * service any undo or redo events.  Clients should call this method
+ * in thier dealloc method, unless they are the sole client of the
+ * undo manager in which case [-removeAllActions] is more apropriate.
+ */
 - (void) removeAllActionsWithTarget: (id)target
 {
   unsigned 	i;
@@ -542,19 +790,36 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Returns the run loop modes in which the receiver registers 
+ * the [-endUndoGroup] processing when it [-groupsByEvent].
+ */
 - (NSArray*) runLoopModes
 {
   return _modes;
 }
 
+/**
+ * Sets the name associated with the actions of the current group.
+ * Typically you can call this method while registering the actions
+ * for the current group.  This name will be used to determine the
+ * name in the [-undoMenuTitleForUndoActionName:] and 
+ * [-redoMenuTitleForUndoActionName:] names typically displayed
+ * in the menu.
+ */
 - (void) setActionName: (NSString*)name
 {
-  if (name != nil && _actionName != name)
+  if ((name != nil) && (_group != nil))
     {
-      ASSIGNCOPY(_actionName, name);
+      [_group setActionName: name];
     }
 }
 
+/**
+ * Sets whether the receiver should implicitly call [-beginUndoGrouping] when
+ * necessary and register a call to invoke [-endUndoGrouping] at the end
+ * of the current event loop.  The grouping is tunred on by default.
+ */
 - (void) setGroupsByEvent: (BOOL)flag
 {
   if (_groupsByEvent != flag)
@@ -563,6 +828,13 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Sets the maximum number of groups in either the undo or redo stack.
+ * Use this method to limit memory usage if you either expect very many
+ * actions to be recorded or the recorded objects require a lot of memory.
+ * When set to 0 the stack size is limited by the range of a unsigned int,
+ * available memory.
+ */
 - (void) setLevelsOfUndo: (unsigned)num
 {
   _levelsOfUndo = num;
@@ -579,6 +851,13 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
 }
 
+/**
+ * Sets the modes in which the reciever registers the calls
+ * with the current run loop to invoke
+ * [-endUndoGroup] when it [-groupsByEvents].  This method
+ * first cancels any pending registrations in the old modes and
+ * registers the invokation in the new modes.
+ */
 - (void) setRunLoopModes: (NSArray*)newModes
 {
   if (_modes != newModes)
@@ -590,11 +869,18 @@ NSString *NSUndoManagerWillUndoChangeNotification =
       [[NSRunLoop currentRunLoop] performSelector: @selector(_loop:)
 					   target: self
 					 argument: nil
-					    order: 0
+					    order: NSUndoCloseGroupingRunLoopOrdering
 					    modes: _modes];
+      _runLoopGroupingPending = YES;
     }
 }
 
+/**
+ * This method performs an undo by invoking [-undoNestedGroup].
+ * If current group of the reciever is the top group this method first
+ * calls [-endUndoGrouping].  This method may only be called on the top
+ * level group, otherwise it will raise an NSInternalInconsistencyException.
+ */
 - (void) undo
 {
   if ([self groupingLevel] == 1)
@@ -609,36 +895,68 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   [self undoNestedGroup];
 }
 
+/**
+ * If the receiver can preform an undo, this method returns
+ * the action name previously associated with the top grouping with
+ * [-setActionName:].  This name should identify the action to be undone.
+ * If there are no items on the undo stack this method returns nil.
+ * If no action name hs been set, this method returns an empty string.
+ */
 - (NSString*) undoActionName
 {
   if ([self canUndo] == NO)
     {
       return nil;
     }
-  return _actionName;
+  return [[_undoStack lastObject] actionName];
 }
 
+/**
+ * Returns the full localized title of the actions to be displayed
+ * as a menu item.  This method first invokes [-undoActionName] and 
+ * passes it to [-undoMenuTitelForUndoActionName:] and returns the result.
+ */
 - (NSString*) undoMenuItemTitle
 {
   return [self undoMenuTitleForUndoActionName: [self undoActionName]];
 }
 
-- (NSString*) undoMenuTitleForUndoActionName: (NSString*)name
+/**
+ * Returns the localized title of the actions to be displayed
+ * as a menu item identified by actionName, by appending a
+ * localized command string like @"Undo <localized(actionName)>".
+ */
+- (NSString*) undoMenuTitleForUndoActionName: (NSString*)actionName
 {
-  if (name)
+  /* 
+   * FIXME: The terms @"Undo" and @"Undo %@" should be localized.
+   * Possibly with the introduction of GSBaseLocalizedString() private
+   * the the library.
+   */
+  if (actionName)
     {
-      if ([name isEqual: @""])
+      if ([actionName isEqual: @""])
 	{
 	  return @"Undo";
 	}
       else
 	{
-	  return [NSString stringWithFormat: @"Undo %@", name];
+	  return [NSString stringWithFormat: @"Undo %@", actionName];
 	}
     }
-  return name;
+  return actionName;
 }
 
+/**
+ * Performs an undo by taking the top grouping
+ * from the undo stack and invoking them.  This method posts an 
+ * NSUndoManagerCheckpointNotification notification to allow the client
+ * to porcess any pending changes before proceding.  If there are groupings
+ * on the undo stack, the top object is poped of the stack and invoked
+ * within a nested beginUndoGrouping/endUndoGrouping.  During this
+ * pocessing, the undo operations registered for undo are recorded on the redo
+ * stack.<br\>
+ */
 - (void) undoNestedGroup
 {
   PrivateUndoGroup	*oldGroup;
@@ -647,34 +965,32 @@ NSString *NSUndoManagerWillUndoChangeNotification =
   [[NSNotificationCenter defaultCenter]
       postNotificationName: NSUndoManagerCheckpointNotification
 		    object: self];
-#if 0
-/*
- *	The documentation says we should raise an exception - but I can't
- *	make sense of it - raising an exception seems to break everything.
- *	It would make more sense to raise an exception if NO undo operations
- *	had been registered.
- */
-  if (_registeredUndo)
+
+  if (_group != nil)
     {
       [NSException raise: NSInternalInconsistencyException
-		  format: @"undoNestedGroup with registered undo ops"];
+		  format: @"undoNestedGroup before endUndoGrouping"];
     }
-#endif
+
   if (_isUndoing || _isRedoing)
     {
       [NSException raise: NSInternalInconsistencyException
 		  format: @"undoNestedGroup while undoing or redoing"];
-      }
-  if (_group != nil && [_undoStack count] == 0)
+    }
+
+  if ([_undoStack count] == 0)
     {
       return;
     }
+
   [[NSNotificationCenter defaultCenter]
       postNotificationName: NSUndoManagerWillUndoChangeNotification
 		    object: self];
+
   oldGroup = _group;
   _group = nil;
   _isUndoing = YES;
+
   if (oldGroup)
     {
       groupToUndo = oldGroup;
@@ -684,16 +1000,18 @@ NSString *NSUndoManagerWillUndoChangeNotification =
     }
   else
     {
-      groupToUndo = [_undoStack objectAtIndex: [_undoStack count] - 1];
-      IF_NO_GC([groupToUndo retain]);
-      [_undoStack removeObjectAtIndex: [_undoStack count] - 1];
+      groupToUndo = RETAIN([_undoStack lastObject]);
+      [_undoStack removeLastObject];
     }
+
   [self beginUndoGrouping];
   [groupToUndo perform];
   RELEASE(groupToUndo);
   [self endUndoGrouping];
+
   _isUndoing = NO;
   _group = oldGroup;
+
   [[NSNotificationCenter defaultCenter]
       postNotificationName: NSUndoManagerDidUndoChangeNotification
 		    object: self];