bzr diff behaviour

[Patrice Guérin]

Hello All,

I use winmerge as diff tool on windows.
When I bzr diff a modified file with its previous revision, I see that 
that the two files to be compared are stored in a temporary directory.
Why bzr diff doesn't compare the true modified file against its revision 
(this one must stored in a temporary directory, I agree)
this should permit to make some more modifications on the diff basis...
Does bzr diff is only intended to be used as "read only" ?

Kind regards
Patrice.