Truncate previous messages in an email thread so they are not shown

[runboxdave]

Is your feature request related to a problem? Please describe.
No.

Describe the solution you'd like
Some email programs display a message but truncate what you see of the rest of the message so that it isn't a distraction. It's actually still there but the window recognises what follows as previous messages (there are indicators in an email source for this) and hides it until you click on something to reveal it. It's particularly useful in threads where you can see the previous messages as separate messages anyway.

The something you click on could be some text that says "See more from sender name" or just "See more". This format is used in Apple Mail.

It could be applied to message viewing in the preview pane in threaded mode but it could also be used in the reply/forward compose windows where perhaps only the last message you are replying to is shown.

[gtandersen]

@runboxdave Could you provide a screenshot of how this looks in Apple Mail?