QMainWindow: Fix unused separator widgets blocking mouse events

We need to hide separator widgets that are unused, otherwise they block
mouse events from the underlying widgets.

Pick-to: 6.2 6.3
Fixes: QTCREATORBUG-24600
Change-Id: I98c6d4860f683a861b89c4cad042bb734f590000
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

2 files changed, 9 insertions, 0 deletions

diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index 3346e0202f..e6c885512f 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -2798,6 +2798,12 @@ QDockWidgetGroupWindow *QMainWindowLayout::createTabbedDockWindow()
 
 void QMainWindowLayout::applyState(QMainWindowLayoutState &newState, bool animate)
 {
+    // applying the state can lead to showing separator widgets, which would lead to a re-layout
+    // (even though the separator widgets are not really part of the layout)
+    // break the loop
+    if (isInApplyState)
+        return;
+    isInApplyState = true;
 #if QT_CONFIG(dockwidget) && QT_CONFIG(tabwidget)
     QSet<QTabBar*> used = newState.dockAreaLayout.usedTabBars();
     const auto groups =
@@ -2820,6 +2826,7 @@ void QMainWindowLayout::applyState(QMainWindowLayoutState &newState, bool animat
         usedSeparatorWidgets = usedSeps;
         for (QWidget *sepWidget : retiredSeps) {
             unusedSeparatorWidgets.append(sepWidget);
+            sepWidget->hide();
         }
     }
 
@@ -2828,6 +2835,7 @@ void QMainWindowLayout::applyState(QMainWindowLayoutState &newState, bool animat
 
 #endif // QT_CONFIG(dockwidget) && QT_CONFIG(tabwidget)
     newState.apply(dockOptions & QMainWindow::AnimatedDocks && animate);
+    isInApplyState = false;
 }
 
 void QMainWindowLayout::saveState(QDataStream &stream) const
diff --git a/src/widgets/widgets/qmainwindowlayout_p.h b/src/widgets/widgets/qmainwindowlayout_p.h
index 55385cc164..66182bf001 100644
--- a/src/widgets/widgets/qmainwindowlayout_p.h
+++ b/src/widgets/widgets/qmainwindowlayout_p.h
@@ -577,6 +577,7 @@ public:
     QPointer<QDockWidgetGroupWindow> currentHoveredFloat; // set when dragging over a floating dock widget
     void setCurrentHoveredFloat(QDockWidgetGroupWindow *w);
 #endif
+    bool isInApplyState = false;
 
     void hover(QLayoutItem *widgetItem, const QPoint &mousePos);
     bool plug(QLayoutItem *widgetItem);