dblatex created this code
\item[{\hyperlink{GtkToolbar}{GtkToolbar}}]
but it should most probably be
[\item{\hyperlink{GtkToolbar}{GtkToolbar}}]
please also see bug #2818215.
As of http://dblatex.sourceforge.net/doc/ch03s05.html dblatex seem to create the index from indexterms. The indexterm tag only marks up something as an index target. The actual index is build inside the index tag. E.g. the docbook xslt style sheet generate an index if the index tag is empty. But if the index tag is not empty, the real index given there should be used. Using the actual index...
