Live Undo (was: RE: [Seaside] odds and ends)

[radoslav hodnicak]

I've actually built a prototype of my application that used live updates 
extensively. No form buttons, every change was persisted immediately as it 
happened. It has no fancy visual improvements but the basic idea is there 
- the user doesn't have to execute actions in steps, saving progress 
manually. I thought it's great, mainly because I got rid of some nasty 
deep copy/transactions stuff that is required for normal form based app.

So I put it online and demoed it. At first people didn't notice much 
difference. But after a while I got questions like "I opened this order 
and started to edit it, but then I noticed it's the wrong one. How do I 
undo the changes?".

Needless to say, I'm back using copies and doing commits and rollbacks. 
Save/cancel buttons are back. When I look at the mentioned example site, 
backpackit.com - yes, it allows me to reorder list items with dragging, 
but it doesn't allow me to undo the changes. I've learned this feature is 
essential for the users (at least for the kind of app I'm developing).

As web apps get more interactive, how do we offer users not only dragging 
rectangles over each other and blinking divs, but also the comfort of 
making mistakes without penalty? While staying smalltalk developers of 
course.

rado