Recent versions have made replying and editing very cumbersome on compact screens

[foresto]

I think this screen shot sums up the problem fairly well:

The Reply banner and preview panel gobble up most of the otherwise-available screen space, leaving only two short lines for the text edit field. The button placed on top of the edit field makes the situation even worse.

Being unable to see the cursor or the just-entered letters makes typing needlessly difficult, and trying to select/copy/paste is sometimes nearly impossible.

I don't remember when the UI was changed to use this layout, but I think it was within the past year.