What I want to do is to change the size of a window and create a window next to it so they are exactly next to each other. In that sense, I need to position to the new window to the top right part of the screen, the way I am doing it is not working (code is below), I need help :)

function () { 

   var viewportwidth = document.documentElement.clientWidth;

   var viewportheight = document.documentElement.clientHeight;

   window.resizeBy(-300,0); 

   window.open(something.htm,

     mywindow,

     width=300,

     height=viewportheight,

     left=(viewportwidth - 300),

     top=0,

     screenX=0,

     screenY=0); 

}