2 files changed, 43 insertions, 1 deletions
diff --git a/src/gui/widgets/qdockarealayout.cpp b/src/gui/widgets/qdockarealayout.cpp
index e83e97e..12f4569 100644
--- a/src/gui/widgets/qdockarealayout.cpp
+++ b/src/gui/widgets/qdockarealayout.cpp
@@ -3321,7 +3321,8 @@ void QDockAreaLayout::keepSize(QDockWidget *w)
 void QDockAreaLayout::styleChangedEvent()
 {
     sep = mainWindow->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, 0, mainWindow);
-    fitLayout();
+    if (isValid())
+        fitLayout();
 }
 
 QT_END_NAMESPACE
diff --git a/tests/auto/qmainwindow/tst_qmainwindow.cpp b/tests/auto/qmainwindow/tst_qmainwindow.cpp
index b4d765c..4eb3c22 100644
--- a/tests/auto/qmainwindow/tst_qmainwindow.cpp
+++ b/tests/auto/qmainwindow/tst_qmainwindow.cpp
@@ -140,6 +140,7 @@ private slots:
     void saveState();
     void restoreState();
     void restoreStateFromPreviousVersion();
+    void restoreStateDockWidgetBug();
     void createPopupMenu();
     void iconSizeChanged();
     void toolButtonStyleChanged();
@@ -1285,6 +1286,46 @@ void tst_QMainWindow::restoreState()
     QVERIFY(mw.restoreState(state, 1));
 }
 
+/*
+    QWidget::setStylesheet() generates QEvent::StyleChange event, which will
+    cause the function QDockAreaLayout::fitLayout() to be called before the layout
+    of MainWindow is activated. This will force the size of dock widgets
+    and the central widget to be calculated using the wrong geometry, which will
+    break the state restored by QMainWindow::restoreState().
+*/
+void tst_QMainWindow::restoreStateDockWidgetBug()
+{
+    QByteArray state;
+
+    //save state
+    {
+        QMainWindow mw1;
+        QDockWidget *dw1 = new  QDockWidget();
+        dw1->setObjectName("Left DockWidget");
+        mw1.addDockWidget(Qt::LeftDockWidgetArea, dw1);
+        mw1.setCentralWidget(new QTextEdit());
+        mw1.show();
+        QApplication::processEvents();
+        dw1->setFixedWidth(101);
+        QApplication::processEvents();
+
+        state = mw1.saveState();
+    }
+
+    //restore state
+    QMainWindow mw2;
+    QDockWidget *dw2 = new  QDockWidget();
+    dw2->setObjectName("Left DockWidget");
+    mw2.addDockWidget(Qt::LeftDockWidgetArea, dw2);
+    mw2.setCentralWidget(new QTextEdit());
+    mw2.restoreState(state);
+    mw2.setStyleSheet("color:red");
+    mw2.show();
+    QApplication::processEvents();
+
+    QCOMPARE(dw2->width(), 101);
+}
+
 //tests the restoration of the previous versions of window settings
 void tst_QMainWindow::restoreStateFromPreviousVersion()
 {