QHeaderView: Reset lastSectionLogicalIdx on clear()

Otherwise we can fail to stretch the last section when adding new
sections.

Task-number: QTBUG-52446
Change-Id: I7eb5267ac500bf4246e57c3e3a43268bb65ef1f7
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 7b393463a6..1a0b417034 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -3465,6 +3465,7 @@ void QHeaderViewPrivate::clear()
     sectionSelected.clear();
     hiddenSectionSize.clear();
     sectionItems.clear();
+    lastSectionLogicalIdx = -1;
     invalidateCachedSizeHint();
     }
 }