On the web, it is extremely difficult to have an undo stack, so I'm talking about "undo" as implemented by appearing to do the action (eg delete), but delaying

On the web, it is extremely difficult to have an undo stack, so I'm talking about "undo" as implemented by appearing to do the action (eg delete), but delaying its actual action while giving the user the ability to undo it. If they take no action (or navigate away, etc.) the action is done. In both of those links I posted, it clearly states well-designed systems have undo.