screenx and screeny?

I want to open a window with full screen size but it don’t set the corner of the window at the upper left corner of the screen. If I look at documentations the screenx and y must do that but it don’t. What do I wrong?
window.open(‘myhtm.htm’,’newwindow’,’width=’+(screen.availWidth)+’,height=’+(screen.availHeight)+’,screenX=0,screenY=0,directories=0,fullscreen=0,location=0,menubar=0,scrollbars=0,status=0,toolbar=0′);