Software that display portionly underlay/background window

Hi all,

I am not programmer. So I am thinking of looking for a software that works like magnifier but able to display what ever window that is underlay or even better background which I think is not possible. I tried to make my desktop as compact as possible. Said like my email, I just want to display the part that are showing new email. If I see that then I know there is new email without email covering large portion of the my desktop so I can do my other task.

Thank you.