Fix selection / focus from Sushi
preview_selection_event() is attempting to set selection on the TreeListRow rather than the TreeListRow's item. This was an oversight after changing the list model to use TreeListRow [1]. Use the existing fuction get_view_item() to properly focus the item. This fixes two issues
- It actually focuses the item rather than simply selecting it
- It scrolls the item into view if it is not currently visible