You can use JavaScript. Save the following code as a .html file:
<html>
<script>
function openWindows() {
window1=window.open('http://google.com/','','width=400,height=300');
window1.moveTo(0, 0);
window2=window.open('http://yahoo.com/','','width=400,height=200');
window2.moveTo(0, 300);
window3=window.open('about:blank','','width=200,height=500');
window3.moveTo(400, 0);
};
</script>
<button onclick="openWindows();">Open Windows</button>
</html>
Open it in your browser and click the button. You should see something like this:
NB: You'll probably have to relax your popup blocker settings. Here's how to change the popup settings on Chrome:
This won't change popup blocker settings for other websites.
On Mac, an extra monitor extends the screen size. For example, if your secondary monitor is arranged to the left of the primary monitor, window4.moveTo(-300, 0);
should do the trick.