XPath expression evaluation question

[<A.M...@sa...>]

I have been doing some development on xslt-process, and am about to start 
work on adding XPath expression evaluation to the debugger using Saxon. 
Given the Saxon code, I hope the actual evaluation may not be too complex. 
What is far from clear to me is the best way of displaying the output of 
an evaluation to the user. If the result is a simple value, it will be 
easy. However, if the result is a node set we need a good way of 
identifying the nodes within the source tree which have been selected. 
Possibilities that have occurred to me (I don't know how easy they would 
be to program, though) are
1. Use the speedbar in some way to display a tree which can be expanded 
and contracted
2. Use the source code in the buffer, and highlight the nodes somehow - 
colour would be the obvious choice
3. Number the nodes hierarchically and display a list of the numbers of 
the selected nodes

Does anyone have any other ideas, or views on a suitable way of displaying 
the evaluated expression.
Thanks
Tony Addyman
----------------------------------
Eur Ing A.M.Addyman
Computer Science
School of Sciences
Newton Building
University of Salford
Salford
M5 4WT
Tel: 0161-295-5067
Fax: 0161-295-5559