In compose window header entries which are automatically filled get their background coloured to indicate that fact. If the entry content is removed with the delete button next to it, background colour is not restored, as one would expect (because it doesn't contain an automatically filled value anymore).
Changes related to this bug have been committed. Please check latest Git and update the bug accordingly. You can also get the patch from: http://git.claws-mail.org/ ++ ChangeLog 2017-09-02 11:45:02.510904830 +0200 http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=d59317fd638efc3a0cdd2a2de0e0c8871745e90f Merge: 310095a 62686c8 Author: Colin Leroy <colin@colino.net> Date: Sat Sep 2 11:45:01 2017 +0200 Merge branch 'master' of file:///home/git/claws http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=62686c8f6f942c79706ed12cdc97ea10aad8c016 Author: Paul <paul@claws-mail.org> Date: Sat Sep 2 10:44:48 2017 +0100 fix bug 3852, 'delete header entry button doesn't restore colour'
Thanks for the fix!