Sets the horizontal alignment, from 0 (start) to 1 (end).
See [the migration guide](migrating-to-breakpoints.html#replace-adapsqueezer)
This affects the children allocation during transitions, when they exceed the size of the squeezer.
For example, 0.5 means the child will be centered, 0 means it will keep the start side aligned and overflow the end side, and 1 means the opposite.
| this |
a squeezer |
| xalign |
the new alignment value |