Last modified: 2012-05-08 13:54:43 UTC
The "Mark thread as read" button has an undo button. Like it, we should have an undo button for "Mark all as read" as well. It is pretty easy to accidentally click the wrong buttons since "Mark thread as read" for the topmost thread and "Mark all as read" nearly touch each other, and time consuming JavaScripts move screen contents around for quite a while without signalling when done, so one may assume that this phase was over before it really is, and thus involuntarily click the place which will later be occupied by the wrong button.
probably better to add this as an "undo" link like google's mail UI where the "undo" link appears in a message box that says "All marked as read, undo" after the action has been performed.
