In a GUI application (desktop or web), there could be multiple editable text boxes in one page/window/whatever. Do people maintain one undo buffer for each text box, or just a global buffer for the entire page/window/whatever? What's the usual practice?
GMail example
There seems to be one global buffer for GMail (or maybe for browsers?). I can't undo email body edits and email subject edits separately.
I think this comes down to what users would expect from the type of app. If you think of MS Word, the undo buffer is per document. On the other hand, in a business app, if the user visits multiple 'pages' to accomplish a given task, then it could make sense to keep a global undo buffer that includes their navigation history.
The Monitored Undo Framework is a .net library that allows you to set up these 'scopes' of undo at whatever level you see fit.
