When you open an HTML document for editing the first time after installing D2H, you are shown the list of HTML editors available on your machine. You may modify this list, if necessary, by choosing the default HTML editor, adding editors if they are not automatically detected, and removing the editors you do not want to use. You can access this list at any time by selecting Tools | Options in the Doc-To-Help Project Editor and clicking the HTML Editors tab.
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Specifying a Default HTML Editor