You could look on Rick's site because he has a lot of helpful information on skins here. I haven't looked through this but it may help you.
Thank you for the help. I found a location in the Properties, Advanced Settings of the HTML Help Layout that
has options for "Plus/Minus Squares." It was greyed out on the default layout but is available if I create a new one.
Note that you can probably coax it to become available in the other layout as well. This is an odd option. In their infinite wisdom, the developers eons ago decided that nobody would want to enable Plus/Minus Squares unless you first had Lines from Root selected. So try enabled Lines from Root.
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