Edit ▸ Redo and the toolbar button followed only the document's Redo.
After Undo in a paragraph or added text box took the typing back, with
no document step to redo, they stayed disabled and only the key could
put the typing back. Redo is now also enabled when the box open on the
page has a Redo of its own: the step redo_in_page_box takes. It doesn't
ask for the box's focus, which the menu has taken by then.