There's an earlier thread that touched on this, but I couldn't
figure out if this question was fully answered.

Using locktitle='yes' in map elements doesn't seem to affect whether
topicref @navtitle values override the actual topic titles. Is this
a bug? Or by design?

There's a lot of code in mappull.xsl that determines what value to
store in @navtitle. That code doesn't run if locktitle='yes', which
seems wrong. Furthermore, in topicmerge.xsl, the @navtitle attribute
is completely ignored anyway--and the topic title or navtitle is
always used as the title.

Looking at mappull.xsl, it seems that the intention was to update
each map @navtitle with its proper value (whether that be the actual
topic title, topic navtitle, or the @navtitle itself) based on
@locktitle, context, and other factors, and then to use the
@navtitles instead of actual topic titles/navtitles during
topicmerge. But again, topicmerge.xsl completely ignores map
@navtitles, wasting all the work that gets done in mappull.xsl.

What's up?