In bug 1097406, telemetry is being collected for the Sync migration, and one thing we'd like to capture is how often the user explicitly dismisses the infobar via [x]. While there is a way to know the infobar was "closed", it doesn't differentiate between the bar closing due to clicking one of the buttons *other* than [x], nor when the bar is removed programmatically. In that bug we've resorted to a hack - we set a flag in our button event handlers. If we see the infobar closed when this flag isn't set we assume it was due to [x] - but that's fragile and doesn't handle programmatic removal. This bug will help us remove that hack (and removal of that hack should really be part of this bug, so we can ensure the facility actually works for our use-case)

From the last I saw of the new proposal for doorhangers, I think we're going to be removing the [X]. It sounds like care about dismissing or taking an action so I guess you also want to catch when someone dismisses by clicking outside of the panel?

(In reply to Matthew N. [:MattN] from comment #1) > From the last I saw of the new proposal for doorhangers, I think we're going > to be removing the [X]. It sounds like care about dismissing or taking an > action so I guess you also want to catch when someone dismisses by clicking > outside of the panel? This is for a <binding id="notificationbox"> rather than a doorhanger (unless I misunderstand)

Bug 1205928 is going to remove any identified need for this bug, and notification bars are going the way of the dodo anyway, so, INVALID.