dynamically resizing Text without a relayout doesn't get the full space

[rcoreilly]

Describe the bug

e.g., in the cogent code status label, if we don't allocate the label itself with Pw(90) (which we do now), then it just gets exactly what it needs at layout time, such that if you then do UpdateRender to update on it, even if the parent widget has plenty of room leftover for it, it doesn't use it.

In principle it should have more Alloc left over beyond its Actual that it uses. But unless it has an actual Grow factor, this is not true: if you don't grow, you don't get extra Alloc or Actual. Maybe need to change this?

Anyway, first need a simple test case and should be pretty easy to fix.

How to reproduce

test case needed!

Example code

Relevant output

Platform

macOS

[kkoreilly]

Even when it has an actual grow factor it doesn't work.