[whatwg] Random comments about UndoManager

Olli Pettay Olli.Pettay at helsinki.fi
Thu Apr 12 09:19:37 PDT 2012

Few random comments about rniwa's UndoManager

"Also, any Web app that tries to mix contenteditable region or text 
fields with canvas or other non-text editable regions will have to 
reimplement undo and redo of contenteditable regions as well because the 
user agent typically has one undo transaction history per document"
- that "typically" isn't true, and I think we should have multiple
   transaction histories, like some browser engines have, and like
   other programs tend to have.

Should it be defined that <input> and <textarea> have implicit undoscope 
by default?

What does "destroy the corresponding UndoManager for the scope." mean?
If JS keeps a pointer to the manager, the object sure stays alive, and
if I read the draft correctly, one can use some of the methods of
a destroyed UndoManager.

Why setting contenteditable clears transaction histories
of descendants? This makes the API a bit harder to understand, but
perhaps there is some reason...

Link "DOM transaction group" doesn't point to anywhere.
And "DOM transaction group" isn't really defined.

If we need really merge option, would it make sense to
have undoManager.transact(transaction); and

DOMTransactionEvent doesn't seem to have proper
dictionary to initialize it.
Why the name DOMTransactionEvent, why not just TransactionEvent?

So the idea is that when contenteditable area is modified by user input, 
UA automatically puts something to the transaction history?


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