Scroll the window up and down and have a look at the title bars of the screenshot.
Unlike screenshots from most other applications you can see the through the screenshot.
In the screenshot above you see the windows calculator (screenshot is taken from Windows 7).
It looks just like a 2$ calculator you can buy anywhere.
You really should know how to use that ;)
You also can change the view mode of the calculator.
For some reason, I prefer the programming one :)
It has some tools like binary value display, also it can handle other number formats like hex.
Screenshots taken with Shotty, Background image by www.bittbox.com