Dear Maintainer,

When writing an RTL subject line in a new message, the subject line
control stays left-aligned -- but it should be right-aligned; text in
the message body does get the correct alignment automatically.

Surprisingly, if the composer window is resized, the subject is then
aligned correctly; but it should align correctly already when the
subject is typed in.

Note that directionality is set correctly automatically; the problem
is only with alignment.

I reported this upstream as https://bugs.kde.org/show_bug.cgi?id=322459