How Internet Explorer downloads HTML-files through Download Manager
This article provides information about downloading documents containing html extension.
Original product version: Internet Explorer 9 and later versions Original KB number: 2846926
When a website wants to raise an Open/Save dialog for a resource, it can do so, by adding a
Content-Disposition: attachment header to the response. If the document to be downloaded contains one of the following extensions, Internet Explorer will only provide Save, Save As and Cancel as choices in the dialog. Internet Explorer will hide the
Open command in case Internet Explorer itself will be the default handler for the extension.
After the download has been finished via the Save button, the information bar at the bottom on the webpage will then provide the possibility to open the downloaded document from the folder to which it had been downloaded.
This behavior is By Design and had been introduced with Internet Explorer 9.
A description about the Content-Disposition, see How To Raise a "File Download" Dialog Box for a Known MIME Type.
In case that another application than Internet Explorer (for example, Notepad.exe) will be default handler for the given extension, the Open-button will be offered and will then launch the application with the document.
A description about the configuration of the default handler is available, see Change which programs Windows 7 uses by default.