Version: KMail 1.6.1 (Using KDE 3.2 BRANCH >= 20040204) (using KDE KDE 3.2.0) Installed from: Mandrake RPMs If you compose a mail in a different virtual desktop as KMail or Kontact, and you sign it or encrypt it, when you click on "Send", the window requesting for your passphrase appears in the virtual desktop where KMail or Kontact is, and not in the current "active" virtual dektop, where you and your composer are. I'm using the "built-in" encryption, and I didn't check with encryption plugin has I don't have one configured for the moment.
I can confirm this with KMail 1.6.2 on debian testing.
The window has most probably wrong parent window specified.
*** This bug has been marked as a duplicate of 74889 ***