[MlMt] Add toggle for a scrollbar in the preview pane (which would turn off auto-scroll)

[Kee Hinckley]

Right now in the compose window, the preview pane stays synchronized 
with what I'm typing.

Sometimes when I'm replying, I'd really like to stay focused on some 
text I'm replying to, but it's off window. One way to do this might be 
to add a toggle in the toolbar that disabled auto-scroll and added a 
scrollbar to the preview pain. Then I could treat it as though I had a 
multi-paned editor. I could type on the left, and read what I was 
replying to on the right.

I have no idea if people would generally find this useful, or if it's 
just me. So take it with a grain of salt. 🌾🙂
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freron.com/pipermail/mailmate/attachments/20180713/fcf9509c/attachment.html>