The data sources should already re-use items, as they are passed the old items, but since data sources are multi threaded, there might perhaps be a situation where the items passed gets updated out-of-order and re-use isn’t perfect (I haven’t been able to confirm this).
Re-using the items, when we use the animation methods of the outline view, does however seem to be very important, because the outline view will neither copy nor retain the items returned from our data source, so we must ensure they stay retained until we have told the outline view that the item no longer exist, so replacing an item with one that is equal but not pointer identical, without notifying the outline view, will cause random crashes.
At least that is my theory.
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