IIRC currently the "Refresh" feature in sniff refreshes all applications, and
resets the tree hierarchy.

When I'm using sniff to look deep inside the tree of a web page inside Epiphany
and click on something that causes a new page to load, sniff retains the
existing hierarchy in the tree view, but supplies dummy blank values for
everything - I get numerous desktop icons without names.

I need to refresh in this case, and then I have to drill down again to find the
frame containing the web page.  This latter part of the process is a pain: lots
of tedious clicking.

Ideally, refresh would happen automatically, but this isn't doable right now
(need to have things like equality/identity working for Node instances, generic
change notifications etc)

So as a workaround, suggest:
(i) implementing a context menu feature on nodes in sniff that force a refresh
in that node and below.  The rest of the treeview expansion state should be
preserved (fairly easy to implement, I think)
(ii) try to preserve treeview expand/collapse state during a refresh (harder, I
think)