function open_window ( url, width, height )
{
	var twidth = width;
	var theight = height;
	var scrollbars = 0;
	
	if(twidth > screen.width - 80)
	{
		twidth = screen.width - 80;
		scrollbars = 1;
	}
	if(theight > screen.height - 80)
	{
		theight = screen.height - 80;
		scrollbars = 1;
	}
	
	var pos_x = (screen.width - twidth - 10)/2;
	var pos_y = (screen.height - theight - 29)/2;
	
	if(typeof(source_window) == "undefined" || source_window.closed)
		source_window = window.open( url,'source_window','menubar=0,toolbar=0,location=0,scrollbars=' + scrollbars + ',screenX='+pos_x+',screenY='+pos_y+',left='+pos_x+',top='+pos_y+',width='+twidth+',height='+theight+',resizable=0');
	else source_window.location.href = url;
	
	source_window.focus();
}

function op ( url, width, height )
{
	open_window ( url, width, height );
}