QHeaderView: fix inconsistent saved state, ignored during restore

The code that updates a section size must also update length,
otherwise saveState can end up saving inconsistent state, and
restoreState() goes to an early-return, not doing anything.

The actual bug was fixed meanwhile because _q_sectionsChanged is called
again, which recalculates length. I still see this only as a safety
measure, every other code path that changes section sizes updates length
right away.

Change-Id: I6cc16261692d93b3640afafef600a5bdff8dca0c
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 5cbf642802..b7048d1616 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -2191,7 +2191,11 @@ void QHeaderViewPrivate::_q_sectionsAboutToBeChanged(const QList<QPersistentMode
     if (stretchLastSection && lastSectionLogicalIdx >= 0 && lastSectionLogicalIdx < sectionItems.count()) {
         const int visual = visualIndex(lastSectionLogicalIdx);
         if (visual >= 0 && visual < sectionItems.size()) {
-            sectionItems[visual].size = lastSectionSize;
+            auto &itemRef = sectionItems[visual];
+            if (itemRef.size != lastSectionSize) {
+                length += lastSectionSize - itemRef.size;
+                itemRef.size = lastSectionSize;
+            }
         }
     }
     for (int i = 0; i < sectionItems.size(); ++i) {