User-adjustable message pane size

[Shaping]

Please add an Appearance configuration feature that allows the user to specify the maximum height of the message window during typing of the message. I type long notes, and I need to see the whole note. I can't do that well without scrolling. If I scroll with the arrow keys, I might jump out of the message into the previous or next. This becomes a problem for editing long messages. The maximum height should be allowed to go to the full height of the Element window client area if desired.

[t3chguy]

Duplicate of #5882