uiSlider bug on uiHorizontalFill

Code like this:

```
uiVerticalStack(150.0) {
uiHorizontalFill {
uiSlider(value = 0, min = -5, max = 5, step = 1) {
this.marks = true
}
uiText("sample")
}
}
```

produces this result:

however simply changing the order of uiSlider and uiText works correctly:

code for that:
```
uiVerticalStack(150.0) {
uiHorizontalFill {
uiText("sample")
uiSlider(value = 0, min = -5, max = 5, step = 1) {
this.marks = true
}
}
}
```

Start by reproducing the two uiVerticalStack/uiHorizontalFill examples from the issue and compare the rendered results when uiSlider precedes or follows uiText. Trace the uiSlider and uiHorizontalFill layout behavior to identify why child order changes the rendering; done means both orders render the slider with marks correctly.

Written by the indexing model from the issue text.