MSHTML是ActiveX文档，它可以host ActiveX控件。
为了显示html页面，推荐host WebBrowser Control。
To replace the menus, toolbars, and other UI for MSHTML, the host should implement the IDocHostUIHandler interface. MSHTML obtains this interface by passing IID_IDocHostUIHandler to the QueryInterface 
method of the host's client site object. If the host does not implement a client site, the host can query the MSHTML document object for the ICustomDoc interface and call the ICustomDoc::SetUIHandler method to set the MSHTML UI handler.
A host of MSHTML can display message boxes, Help UI, and all in-place active UI on behalf of MSHTML by implementing two interfaces, IDocHostUIHandler and IDocHostShowUI