UIText: Background dimension doesn't adjust to multiline text

val errorBlock = uiText("This is a test\nblahblah blh blah blah") {
bgcolor = Colors.RED
alignY(root, 0.8, true)
centerXOnStage()
}

Start by reproducing the issue with the provided uiText snippet and its multiline string, red background, and alignment settings. Trace how uiText measures multiline content and sizes its background; done means the background covers all rendered lines, with the single-line behavior preserved.

Written by the indexing model from the issue text.