When changing the Message Preview Pane from 'below the message list' to 'next to the message list', the new preview pane is not visible (has width 0). It also happens the other way round and it can be seen each time you open KMail and you switch layouts. There is an easy workaround if you know that you need to drag the thin bar at the window's edge, but it's not really clear. I think we should add a default size (and maybe a minimum size). Reproducible: Always
screenshot please
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of kmail2 (version 5.0 or later, as part of KDE Applications 15.12 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.