On Jan 16, 2014, at 11:51 , Matthew LeRoy <mle...@minitab.com> wrote:
> - (NSUndoManager *)windowWillReturnUndoManager:(NSWindow *)window
> {
> if (window == [self window])
> {
> return [[self inspectedDocument] undoManager];
> }
>
> return nil;
> }
It seems to me that this is fundamentally wrong. There’s already an undo chain
starting at your document *window*, connecting to the undo chain in your
document. This is conceptually true even if it might not in itself be screwing
things up in the case.
For example, imagine that your document window also had a text field in which
you can type when the inspector is not key. While the text field is active,
there are undo items *in the document’s undo chain* for undoing typing. Typing
in text fields in the inspector creates typing-undo actions *also* in the
document’s undo chain, and things could get nasty from there — you’ve created a
branching chain, but it can’t really do that.
At least, I think this is what can happen. You might be able to reason that
nothing actually going wrong because the actual sequence of events always
discards one branch of the chain when starting another, but this still seems
like a flawed approach to me.
The other problem, more mundane but probably more directly underlying the weird
behavior you’ve seen, is that the above code tells the *panel* window what its
undo manager is, and the window remembers this. (You saw this yourself:
> It seems that if -windowWillReturnUndoManager: returns nil, then the method
> never gets called again.
Indeed, when it saw a nil return, the window created its own undo manager, and
then never asked again.)
So, it seems to me, you gave the panel window an undo manager from one
document, and then the panel is going to use that for any subsequent document
that it targets. Hilarity ensues.
I think the proper course of action is:
1. Have the panel’s window delegate method ‘windowWillReturnUndoManager:’
return nil, or don’t implement it. This will give you a unique, single undo
manager for the panel itself, which will be used for typing-undo in the panel’s
text fields, and nothing else.
2. When a change is made to the document via the inspector, make sure the
corresponding undo action is created in the context of the correct document
undo manager. You will have to pay attention to the possibility mentioned
above, if it can occur, that the document window itself may be in control of
the top of the document undo chain.
Or, to put it more simply, make sure that inspector panel document changes are
actually made by the document window controller, not by the panel window
controller.
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