Measuring child with Infinite or Available height in Auto mode

[Ranjith-RKD]

Hi folks,

I'm building a custom Expander control that can contain multiple children — for example, a ScrollView or a Grid, each holding a Label.

Now, suppose the Expander is placed inside a parent with a fixed size, say Width=500 and Height=500.

When measuring its children, if I pass infinity, then controls like ScrollView or Grid (with a multi-line Label inside) often return only the space they need — say 50 in Width.
But if I measure them with 500, they report 500 — the full available size — even if they only need a small portion.

That seems counterintuitive — you’d expect infinite size to result in larger measurements, not smaller.

This behavior leads to layout confusion. For example:

But when I place a ScrollView or Grid inside my Expander, if the Expander measures with infinity, it ends up getting a small size like 50.
If it measures with 500, it gets 500 — even when the child doesn't need that much space.

What should I do — measure with infinity, or report this as an issue?