There's a patch languishing upstream here to fix this:
This bugzilla is a reminder to myself to consider applying it, and to
try and get upstream to adopt it.
Note that it adds a new as yet untranslated UI string ("Select
Subthread"), though that part can be disabled.
(too late to go into Evolution 2.4; hopefully it can go in Evolution 2.6)
This has been resoved NOTABUG by upstream. Resolving here as UPSTREAM; I want
to minimize our difference from upstream on this; take the battle there if you
want it reopened.