This was caused by confusing naming of frame overlay feature. Correct flag to use is `sseq->flag & SEQ_SHOW_OVERLAY`, not `ed->over_flag & SEQ_EDIT_OVERLAY_SHOW`.
This was caused by confusing naming of frame overlay feature. Correct flag to use is `sseq->flag & SEQ_SHOW_OVERLAY`, not `ed->over_flag & SEQ_EDIT_OVERLAY_SHOW`.