Secondary windows are only relevant in Microsoft HTML Help CHM files. They are used to display individual topics in external windows.
Avoid using hyperlinks in secondary windows. Although an external window is a full instance of the help viewer hyperlinks between it and the main help can quickly get very confusing for the user.
In HTML Help you can use additional help window definitions to display topics in external windows when they are opened with hyperlinks. Topics can only be displayed in external windows in HTML Help CHM files and the help window settings have no effect in other help formats.
Important: Help window types can only be used in hyperlinks.
You cannot link open topics from other CHM files in external windows.
1.In the Project Explorer go to Configuration > Microsoft HTML Help > Help Windows and create at least one secondary help window type definition with Add.
Adjust the settings of the window definition as you want the external window to appear – in addition to the size and position you may want to switch off navigation controls etc. in the help window definition's HTML Help Options tab.
2.In the HTML Help Options tab activate the option Links to secondary help windows open a new help window.
3.When you create a hyperlink to a topic specify the secondary help window type with the Window: setting in the link definition.
When the user clicks on the hyperlink the target topic it will now be displayed in an external window in HTML Help, with all the settings defined for the window type in step 1.