[O] narrowing to subtree in navi-mode

[Matt Price]

I am trying to rewrite my org-writers-mode to use a navi-mode buffer
as a guide for the org-mode buffer

In navi-mode, it is possible to narrow the original ("twin)) buffer
using the quick ommand "r".  However, doing so also narrows the
navi-mode buffer, so that only the current heading is visible.

I would like to keep the full tree visible in the navi-mode buffer
while narrowing the original org buffer.  I wonder if this is
possible? In particular, I wonder if I am confronting an underlying
limitation in occur-mode, on which navi-mode is based.

 Thanks for your help!
Matt