//显示帮助tip
function displayHelp()
{
	var helpStr = "";
	helpStr += "使用帮助<br />";
	helpStr += "最佳浏览分辨率: 1280 * 1024<br />"
	helpStr += "图例说明:<br/>"
	helpStr += "<table border='1' align='center' width='100%'>";
	helpStr += "<tr><th>图例</th><th>图例说明</th></tr>"
	helpStr += "<tr><td><img src='images/white.jpg'></td><td>正常液位油罐</td></tr>";
	helpStr += "<tr><td><img src='images/yellow.jpg'></td><td>超过最低/高安全液位油罐</td></tr>";
	helpStr += "<tr><td><img src='images/red.jpg'></td><td>超过最低/高极限液位油罐</td></tr>"
	helpStr += "<br />";
	helpStr += "操作说明:<br />";
	helpStr += "<tr><th>按键</th><th>说明</th></tr>";
	helpStr += "<tr><td>M</td><td>右转</td></tr>";
	helpStr += "<tr><td>N</td><td>左转</td></tr>";
	helpStr += "<tr><td>+</td><td>放大</td></tr>";
	helpStr += "<tr><td>-</td><td>缩小</td></tr>";
	helpStr += "<tr><td>Page Up</td><td>增加仰角</td></tr>";
	helpStr += "</tr><td>Page Down</td><td>降低仰角</td></tr>";
	helpStr += "</table>"
	
	
	var ll = (screen.width);
    var tt = (screen.height);
	var oPopup = window.createPopup();
	var oPopBody = oPopup.document.body;
	oPopBody.innerHTML = helpStr;
	oPopBody.bgColor='fffacd';
	oPopup.show(ll, tt, 360, 385, document.body);	
}