The button that appears when you mouse over a notification, that lets you mark the notification as read, could use some improving.

First, it's not actually good that it appears on top of the notification when you mouse over the notification. This makes it harder to read the notification while you may be getting ready to click on the notification. So it should be moved out of the way, or given some alpha-opacity or something to make it less intrusive over the actual notification text.

Secondly, I find it weird that it pops out a little more when you mouse over the actual button. Is that supposed to mean something? I'd rather see it have minimal opacity that is brought to full opacity on mouseover rather than the jumping a little further left as it does now.

Perhaps with the right icon and placement, it won't need all the white background either. What's wrong with a tiny little circle-x or circle-check button of some sort squeezed into the corner and out of the way. Reference how Facebook does this with their notifications as an example.