The expand/collapse button on the floating panel was removed earlier, but Esteban's overlay-controls refinement reintroduced the `onTogglePresentationMode` ivar and Verovio merge kept the matching `togglePresentationMode()` / `expandFromStrip()` chain in the window delegate. Nothing wires or fires them now — the only entry into the expanded panel is the popover's mini-visualizer click. This deletes the dead callback ivar, the toggle method, and `expandFromStrip` so future readers don't chase a code path that no caller can reach. `collapseToStrip` stays — it's still called from `dockOnMenu`. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>