事件发生序列
下图展示了IE的事件发生序列.但这仅仅为不包含帧的普通网页浏览. (没有包含诸如 ProgressChange, CommandStateChange, OnToolBar, 等等事件.)不是所有事件都会被激发. 但是 BeforeNavigate2 和DocumentComplete 每次浏览都会被激发.
Figure 7-5. The sequence of events fired by the WebBrowser control during a typical navigation.
http://blog.csdn.net/shanhe/article/details/451681
