title: how to get the back image of a window?
body: <p>We are building a program for visual impaired people, the aim is to replace some features of the screen, like colors, shapes or else. Currently, we have a full-screen window, we grab a snapshot of the screen (through the robot java library) and we reproduce it to the full-screen window. When we try to take the next screenshot, obviously the image we got refers to the current full-screen window. We need to get the back of the full-screen window, after an extensive research we had no success on find a way to do so. </p>
  
  <p>Do you know of a library or a way to achieve this, possibly (but not necessarily) in java?</p>