I’m loving the new notification DISMISS button and chevron - thanks for implementing it! 
I know this will only work on desktop, but can you add mouseover helper text along the lines of the DISMISS ALL button on the notifications page? That way, at least on desktop, people will have a chance to find out what the button is for before the select it.
Ok I updated it to have the better tooltip and look at local cache.
Awesome! I like it.
FYI, on meta, the notifications menu is quite long for me right now, so on my laptop the “log out” and “dismiss” links are below the fold. When I scroll down in the menu to get to them, the “dismiss” link gets covered a bit on the right side by the vertical scroll bar.
See screenshot - on meta and my site there are 12 items, but the titles are longer on meta so they go onto 2-3 lines, which I suspect is what makes the menu get a bit too tall to fit on my screen. Maybe to avoid this it needs to be 10 items not 12?
Or maybe some guilty parties (me, especially) should avoid writing such long titles? 
Your example shows notifications that are 2 or 3 lines high, which is more than our rough estimate accounts for:
Ah - I am now realizing that the notification pulldown height depends on the height of the window. So my screenshots don’t make any sense since I was moving them around between screens and resizing them to try to figure out what is going on. But as long as you click the notification menu and don’t resize, it displays them properly.
But if you do resize the window before clicking away from the notification window, you lose access to the bottom part of the menu. This is unavoidable, presumably, or at least worth living with.
