bug#42347: Feature request: Visual block attribute for overlays

[Drew Adams]

> The previous behavior can be obtained with the ":extend t" face attribute.

Only on an individual basis, right?  If you want to
get the previous behavior everywhere, do you need
to change every overlay?

Or is there an option for that?  If not, why not?

And is there a way to get the previous behavior by
default, and something that does the opposite of
`:extend' for individual cases where you want the
new behavior?

If not, why not?