The Target dropdown keyed panes off feedBackSplitscreen.panelIndexFor,
which can return the focused index for any canvas — so both split panes'
keys ping-ponged, rebuilding the <select> every frame (flicker) and
listing wrong/duplicate entries. The registry also never dropped panes
from a prior song or a closed split.
- Key each pane by a stable per-renderer-instance id (_paneUid, assigned
once in init) instead of the split panel index.
- Prune panes not reported within ~1.5s (song change / split teardown).
- Mark the dropdown dirty only when the pane SET changes, not on every
per-frame re-report, and skip rebuilding while the <select> is focused.
- Hide the Target row entirely when there's a single pane.
- Label panes by arrangement name, falling back to "Pane N".
Per-pane overrides are now session-only (keyed by ephemeral instance ids),
so they're no longer persisted to localStorage.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: topkoa <topkoa@gmail.com>
