一个极简单的firefox扩展的例子(入门级) -- 跟firefox打招呼

这是一个很简单的例子,已经入门了的就不用看了.
安装这个扩展后重启firefox,在浏览器的网页显示区点右键,可以看到下拉菜单中有一个菜单项"HelloFirefox",点击这个选项,会出现一个"Hello Firefox!"的提示框.
代码很简单,就不作什么解释了.
安装文件install.rdf代码如下:

<?xml version="1.0"?>

<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:em="http://www.mozilla.org/2004/em-rdf#">

	<Description about="urn:mozilla:install-manifest">

		<em:id>{3912615B-BD5B-40aa-942C-36C4F66AA378}</em:id>
		<em:name>HelloFirefox</em:name>
		<em:version>0.1</em:version>
		<em:description>Say hello to FIREFOX!</em:description>
		<em:creator>Land Wen</em:creator>
		<em:homepageURL>http://www.dotdee.com</em:homepageURL>
		<em:iconURL></em:iconURL>
		<em:aboutURL></em:aboutURL>
		<em:updateURL>http://www.dotdee.com/update.rdf</em:updateURL>
		
		<em:file>
			<Description about="urn:mozilla:extension:file:hellofirefox.jar">
				<em:package>content/hellofirefox/</em:package>
			</Description>
		</em:file>

		<em:targetApplication>
			<Description>
				<em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
				<em:minVersion>0.7</em:minVersion>
				<em:maxVersion>1.5</em:maxVersion>
			</Description>
		</em:targetApplication>

	</Description>

</RDF>

功能实现文件hellofirefox.xul如下:

<?xml version="1.0"?>

<overlay id="hellofirefox" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<!-- 添加自定义的菜单子项 -->
<popup id="contentAreaContextMenu">
  <menuitem id="hellofirefox" label="HelloFirefox" accesskey="H" oncommand="alert('Hello, Firefox!');"/>
</popup>

</overlay>

完整文件在附近里.