Thanks for the report, it was definitely a Studio bug.
The built-in Page Setup and Print dialogs draw their OK/Cancel captions flush-left inside the button because Avalonia's Fluent theme leaves button content alignment unset, and these two dialogs were the only built-in ones that didn't set it explicitly. Fixed for the next release: https://feedback.objo.dev/bug/1387
Both dialogs now centre their button captions, matching the Objo Button control and the other built-in dialogs.
