Open a help project file, and then click Add/Modify Window Definitions.
Add/Modify Window Definitions
Adds or edits window definitions and the general appearance of the HTML Help Viewer.
In the Create a new window type named box, type a window name for the Help Viewer.
Click the Navigation Pane tab, and in the Window type box, select the Help Viewer by the name you gave it in step 2.
If you want to change the default width for the left pane of the Help Viewer, enter a new width in the Navigation pane width box.
Select the Open with Navigation pane closed check box if you want the compiled help file to open with the Navigation pane closed.
Select the Auto sync check box if you want the heading or topic in the Navigation pane to automatically synchronize with whatever topic appears in the Topic pane.
In the Default tab box choose which tab will appear in the Navigation pane when the help file is first opened.
In the Tabs area, select the tabs that you want to appear on the Navigation pane.
Notes
To customize the Help Viewer, you must create a a new window. Any changes to your new window are then noted in the [WINDOWS] section of the project (.hhp) file.