The overlay ids that should be active at index. Pure: the index is NOT clamped here, since an out-of-range index is a caller mistake worth seeing as "nothing active" rather than silently showing the nearest step. An empty sequence is always empty.
index
The overlay ids that should be active at
index. Pure: the index is NOT clamped here, since an out-of-range index is a caller mistake worth seeing as "nothing active" rather than silently showing the nearest step. An empty sequence is always empty.