Weird entrecard screen

When I click on a link, a lot of the time I will middle-click on it in Firefox, to open it in a new tab. Well, I accidentally hit the middle-click (the button under the scroll wheel) to drop on someone's entrecard, and this is what opened in the new tab.

When the button says "thanks", it is inside an iframe with the background image the yellow button. So when it is opened in a new screen, the yellow button background just fills the entire screen. Fun.