If you are using a screen printing and then crop the part you want by using Photoshop or MS Paint. With this trick you will learn how to capture only the active window.
WHAT IS ACTIVE WINDOW?
Before you learn this trick, it is a good idea to really know what ‘active window’ means.
An active window is the currently focused window in the current window manager or explorer. Different window managers specify the currently-active window in different ways and allow the user to switch between windows in different ways. For example, in Windows, if both Notepad and Mozilla Firefox are open, clicking in the Notepad window will cause that window to become active. In Windows, the active window is indicated by having a different color title bar.
How to Take a Screenshot of Only the Active Window
by default, when you tapping Print Screen button it takes a screenshot of your whole screen. So to be more specific to take a screenshot of active window only. just you need to hold ALT while pressing Print Screen button (ALT + Print Screen). Now a picture of the Active window is copied and you can paste it wherever you'd like.
image via Phil Sexto