This change will allow the BColumnListView to have multiple rows added or removed at the same time. Without this, applications using the BColumnListView will need to add and remove rows one by one which, for longer lists with complex columns, is a performance problem; an example being HaikuDepot. Note that this change does not amend the formatting style on the class's source. Change-Id: I72303c8b069b686251c3a65af7ae45c8884d5637 Reviewed-on: https://review.haiku-os.org/c/haiku/+/9056 Reviewed-by: waddlesplash <[email protected]> Tested-by: Commit checker robot <[email protected]> Reviewed-by: Andrew Lindesay <[email protected]>