PanelBar uses some tricks to maintain the initial item's position while all items are expanding. For that to work, the initial item (and maybe every item, but I'm not sure) must not be removed by the ListView because PanelBar relies on the item's position for calculation. Ideally, because PanelItemRow expands the ListView to match its children, no item should fall out of its view. However, upon testing, the rightmost item can fall out of view and get destroyed under some circumstances. To solve this, ListView.delayRemove is bound to the transition's running state, so that it won't be removed while it's expanding (or retracting, but that probably doesn't matter). Fixes ubports/unity8#132.