Taking screenshot of a selected region window or fullscreen sometimes feels impossible with the native windows or mac shortcuts, but here is the good news you can use the free open source screenshot program both in Windows and MacOS:
GREENSHOT is a free open source screenshot program which effortlessly captures screenshots of a specific area, window, or entire screen, and even capture full (scrolling) web pages in Internet Explorer.
Easily add annotations, highlights, or blur parts of the screenshot.
You can export the screenshot in multiple ways: save it to a file, print it, copy it to the clipboard, attach it to an email, send it to Office programs, or upload it to photo-sharing sites like Flickr, Picasa, and more.
