Consider changing the position of the close button in the Overview
Feature summary
I think it looks redundant to have two close buttons in the Overview. People might be confused that they can click the smaller button to click the application until they hover over it.
How would you like it to work
Maybe the close button in the Overview will be placed over the actual close button of the app. This will reduce redundancy and reduce confusion. In how it looks, I think it subjectively looks good.
Relevant links, screenshots, screencasts etc.
I did some simple mockups: (This is what it currently looks like ^ )