Update to "Alerts" semantics

[Laird]

New member @"Durward"#545 prompted me on an issue I'd long been aware of but never gotten around to fixing. It's interesting in this sense what new minds can bring to bear.

In any case, the issue (as Durward and I see it) was:

The semantics of the modal pop-up (accessed by clicking "Alerts" in the header) were different to those of the full listing (at `alerts.php`, accessed via the modal pop-up by clicking "View Alerts" in the pop-up's footer).

In particular:

1. The modal pop-up did not affect the (un)read status of alerts, whereas simply visiting the full listing marked all unread alerts as read.
   
2. The modal pop-up visually dimmed read alerts, whereas the full listing did not.
   

We brought the semantics of the full listing into alignment with those of the modal pop-up, and, thereafter, added a "Mark All Read" link to both.

In case it interests anybody, the means by which this was done are described in the MyBB community forums tutorial MyAlerts: Align pop-up dialogue semantics with full page listing + more.

I hope that this improves the "alerts" experience for members. Feel free to voice your opinion.

Thanks. I was kind of slow in figuring this out. I did eventually realise that there was a need for a "mark all as read" button and found the workaround. Not long ago I thought it seemed to have stopped working, but I wasn't getting many alerts simply because of my low quantity of recent postings. Your work and the explanation in this thread resolves both of those aspects, I think.