This only applies to expanded enums in a property split layout.
Expanded enums are especially troublesome when the layout is narrow. So
idea here is to let them spread over multiple rows in such cases,
keeping them usable.
The layout width used as threshold is just an estimate (taking DPI and
zoom factor into account). For a smarter solution we'd have to do this
after the layout was entirely calculated, potentially re-running the
layout afterwards.
In some cases this behavior may not be needed ,e.g. the color-depth
property for image settings has short labels which fit nicely even in
narrow layouts. So this patch makes the behavior optional too by adding
a expand_no_responsive option to UILayout.prop().
D10505 proposed such a solution for its layouts. I think it's something
that could work well without being too intrusive. So worth checking if
we want this as general layout feature.
