In HTML Help you can use additional or "secondary" help window definitions to display topics in external windows. An external window is a full-featured help viewer window that is displayed separately from the main help window. In a way, external windows are like popups, but they have all the features of the main help viewer.
External windows are only supported in HTML Help and can only be activated by specifying a secondary help window in the definition of a hyperlink to the topic you want to open in an external window.
In HTML Help you must activate secondary windows to be able to display external windows. This is a global setting – when you activate it all links to topics specifying a secondary window will be displayed in external windows. The appearance and features of the external window are defined by the HTML Help Options settings in Configuration > Microsoft HTML Help > Help Windows.
Note that in HTML Help using a secondary window in a hyperlink does not change the background colors or the topic template, which are controlled by the topic's HTML page template, not by the help window. The buttons, controls, window position and size from the secondary help window definition are all used, however.
•To display an external window with different background colors in HTML Help you must define the topic file itself with an HTML page template that has different background colors.
It is not possible to create topics in the TOC that automatically open in external windows when you click on them. You can only activate secondary windows by specifying the window type in a hyperlink definition.