function popup(page, title, width, height, scrollbar)
{	
	var screen_height = screen.height * .5 - (height *.5);
	var screen_width = screen.width *.5 - (width * .5);
	
	var newWin;
	
	if(width > screen.width || height > screen.height)
		newWin = window.open(page,title,'status=no,resizable=yes, width='+screen.width+'px,height='+screen.height+'px,scrollbars =yes');
	else				
		newWin = window.open(page,title,'status=no,resizable=yes, left ='+screen_width+', top ='+screen_height+', width='+width+'px,height='+height+'px,scrollbars ='+scrollbar);
		
		newWin.focus();
			
}