Clear alerts after viewing what the alert is about

[Money]

Currently (i believe) alerts persist until you click the alert icon and are brought to the "recent alerts" screen, even if you've already checked what the alert is referring to. I'd like to suggest changing it so if you check the post/pm the alert is about, the alert is also cleared. This way, you don't have old, irrelevant alerts atop the page, obscuring the actual number of things you need to attend to

(Mini sub suggestion: only display the red box with the number if you dont have zero alerts, so it's more obvious when you get a new one)

[Kritter]

There'd need to be some JavaScript trickery or something to hide the red box if you have 0 alerts and that's beyond my scope.