As the title says: Saving mails which are marked to be inline-encrypted as drafts works correctly, the message is correctly shown after entering the decryption credentials. Yet editing does not work, since the message body is not decrypted in the editing window. This happens with KMail 4.7.4 and is fullr reproducible here.
Internally the same methods are used for forwarding, replying and editing an email. *** This bug has been marked as a duplicate of bug 298911 ***