Version:           1.11.2 (using KDE 4.2.2)
Compiler:          gcc 4.3.3 x86_64
OS:                Linux
Installed from:    Gentoo Packages

with a simple thread like:
a
`-- b
    `-- c

if the thread is collapsed at the thread starter ("a") and the "a" e-mail is selected, then trying to view source on the e-mail "a" does not work (hitting the V shortcut key).  if it's expanded, then it works fine.

the bug is only observed on the thread starter ... if messages under "b" are collapsed, viewing the source on the "b" e-mail still works fine.