Ribbon tooltips died the day the panels moved into CollapsePanels
(v0.7.6): its overlay() started with `self.open?`, so with no flyout
open — the normal state — it returned None and swallowed every child
overlay, and iced tooltips ARE overlays (#411). Buttons still hovered
and clicked, which is why only the tips were missing. With no flyout
the widget now collects the shown variants' overlays into a Group,
borrows split per panel slot.
Co-Authored-By: Claude Fable 5 <[email protected]>