How to reproduce:
open new mail
write several lines so the written text fills more than the displayed area
delete text until the displayed area is empty.

Actual Outcome:
The displayed area does not automatically follow the curser by deleting more than the displayed text.

Expected Outcome:
One should always see the letters that are being deleted. So the display area should follow the curser. (The same way it does by writing new lines instead of deleting them)