tl;dr: rotate text only and report fixed container size
The hierarchy of the User Widget that serves as the book spine element:
- the
Size Boxreports fixed size the parent container will see and should be set to the maximum allowed size in px we ever want to see; text length exceeding this value will spill/clip (if you let the border clip it) but can be auto-adjusted with a scale box (not included here):
- the
Borderkeeps its content centred:
- the
Text Blockis rotated:
Did not test it thoroughly but this should allow other containers to handle it more gracefully now: