That's amazing, with hot keys we can get the windows picture easily on Mac PC, pressing and holding hot-key “shift+command+4” there will be a “+” on the screen, you can choose the windows you want to cut out by moving the mouse, pressing shift+command+3,you can catch the whole screen.

I have had a try with this way, great! I just find this new way yesterday, I can't help to showing here.
With Shortcut keys really can save much time on our computer work.