function openwin(url,width,height) {
	if (!width) width = 400;
	if (!height) height = 200;
	var newwin = null;
	LeftPosition = (screen.width) ? (screen.width-width)/2 : 0;
	TopPosition = (screen.height) ? (screen.height-height)/2 : 0;
	newwin = window.open(url,"newwin","width="+width+",height="+height+",resizable,scrollbars,left="+LeftPosition+",top="+TopPosition+"");
}

function show_block(block_name,status) {
	if (document.getElementById) {
		document.getElementById(block_name).style.display = (status == false) ? 'none' : 'block';
	}
}

function BlockOver(BlockName,Class) { 
	if (document.getElementById && document.getElementById(BlockName)) {
		document.getElementById(BlockName).className = Class;
	}
}