用IE打开网页,点网页中一个按钮,出来一个对话框,这种对话框是调用什么函数产生的?该如何处理

用IE打开网页,点网页中一个按钮,出来一个对话框,这种对话框是调用什么函数产生的?
我HOOK了MessageBoxA   和   MessageBoxW,都无法钩住这种对话框,请问这个对话框是调用了什么函数??如何才能HOOK到?

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up
i don 't known
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two methods:

1 implement IDocHostShowUI,which has a ShowMessage method.
2 when DocumentComplete event fires, override window.alert/comfirm/prompt
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//btw: why i can 't input chinese char???

编码问题
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yes, it is the wrong encoder.
doesn 't anybody come to solve the problem?