I built one using a table and iframes. The challenge seems to be that I have to use an iframe because there is only one variable, page.body, which generates the page content for BOTH the index (links) and normal pages.
The template file generates a mini webpage with a sidebar with links. It works, but it isn't the prettiest. Plus. I hate using an iframe as it reduces scalability, but I can't think of another way to do it.
I'd love just being able to do like <td src="links.html">, but apparently tables can't handle that.
In order for this to work your index has to be called "links" in export options.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>[% TITLE %]</title>
<meta name='Generator' content='Zim [% zim.version %]'>
<style type='text/css'>
a { text-decoration: none }
a:hover { text-decoration: underline }
a:active { text-decoration: underline }
strike { color: grey }
tt { color: #2e3436; }
pre { color: #2e3436; }
h1 { text-decoration: underline;
color: #4e9a06 }
h2 { color: #4e9a06 }
h3 { color: #4e9a06 }
h4 { color: #4e9a06 }
h5 { color: #4e9a06 }
span.insen { color: grey }
</style>
</head>
<!-- Header -->
[% IF page.is_index %]
[% ELSE %]
[% IF prev %]
[ <a href='[% prev.file %]'>Prev</a> ]
[% ELSE %]
[ <span class='insen'>Prev</span> ]
[% END %]
[ <a href='index.html'>Index</a> ]
[% IF next %]
[ <a href='[% next.file %]'>Next</a> ]
[% ELSE %]
[ <span class='insen'>Next</span> ]
[% END %]
<hr>
[% END %]
<!-- End Header -->
<TABLE BORDER="0" width="100%">
<TR>
<TD align="left" valign="top" width="25%">
[% IF page.is_index %]
[% ELSE %]
<IFRAME frameborder="0" marginwidth="0" marginheight="0" width="100%" height ="600" align="left" scrolling="No" SRC="[% notebook.root %]/links.html"></IFRAME>
[% END %]
</TD>
<TD valign="top">
[% IF page.is_index %]
<font align="left">
<base target="_top">
[% page.body %]
[% ELSE %]
<u>[% page.heading %]</u>
[% page.body %]
</TD>
</TR>
</TABLE>
<hr />