Thunderbird: use autoscroll everywhere

Hi!

The autoscroll feature (scrolling window by mouse with wheel pushed) is
very useful feature.
But it works only on viewing messages body.
It doesn't work on letters lists (for example, inbox) window, nor when you
composing a message
and want to quickly scroll down when you replying to long text.
So I suggest to enable autoscroll on every window or textbox that can be
scrolled.

Thank you.