The Screen API has been lately added in order to better handle window sizing and positioning on single or multiple screens. Run the following code:

var gui = require('nw.gui');
gui.Screen.Init(); // Screen API is a Singleton
var screens = gui.Screen.screens;

You'll get an array of screen objects. Each screen object has the following structure:

screen {
  // unique id for a screen
  id : 69673536,

  // physical screen resolution
  bounds : {
    x : 0,
    y : 0,
    width : 1280,
    height : 800
  },

  // useable area within the screen bound
  work_area : {
    x : 0,
    y : 23,
    width : 1280,
    height : 773
  },
  scaleFactor : 1,
  isBuiltIn : false
}

You can easily access any of these properties in order to improve the user experience. Let's say, for example, that you want to position your window in the top-right corner of the screen. On Microsoft Windows, you would probably proceed as follows:

var gui = require('nw.gui'),
  currentWindow...