It would be very useful to be able to select text from an existing message, in order to copy/paste parts of it into a new message, for instance.
I know :) I need to find a method to make copy/paste from label. It's on my todo list too
I have submitted a patch for this at https://phabricator.kde.org/D29690 Has been few years since I submitted a patch to a KDE project, I hope I didn't miss something obvious in the review request :)
Fixed by https://commits.kde.org/ruqola/62017fc7c778fbc549bc0343bc650761e12f5b8b