It appears that when I type in overwrite mode in the kmail composer (plain text mode), hitting <Space> does not overwrite the character under the cursor (the space is inserted before it instead).
I confirm it.
Git commit b8043dc72d080727191cb434852008d9f4c6b700 by Montel Laurent. Committed on 23/07/2014 at 05:46. Pushed by mlaurent into branch 'KDE/4.14'. Fix Bug 337713 - kmail editor overwrite mode: space key does not overwrite FIXED-IN: 4.14 M +18 -6 messagecomposer/composer/kmeditor.cpp http://commits.kde.org/kdepim/b8043dc72d080727191cb434852008d9f4c6b700