When calling QTreeView::hideColumn() the row heights are not
recalculated. This can lead to rows which are unnecessarily high due to
hidden columns may contain large (e.g. multiline) content. The same
applies to showColumn() - there the row might be to small.
Hiding columns directly via QTreeView::header()->hideSection() is not
covered by this patch since QHeaderView has no way to inform about
newly shown/hidden sections.
Task-number: QTBUG-8376
Change-Id: I20b1198e56e403ab8cf649af76e5e2280821dd68
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>