3 files changed, 12 insertions, 1 deletions
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 7a8fcc2c76..4350572c45 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -2088,8 +2088,11 @@ void QComboBoxPrivate::setCurrentIndex(const QModelIndex &mi)
         currentIndex = QPersistentModelIndex(normalized);
     if (lineEdit) {
         const QString newText = itemText(normalized);
-        if (lineEdit->text() != newText)
+        if (lineEdit->text() != newText) {
             lineEdit->setText(newText);
+            if (lineEdit->completer())
+                lineEdit->completer()->setCompletionPrefix(newText);
+        }
         updateLineEditGeometry();
     }
     if (indexChanged) {
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 20dd4c976c..e71b9616fc 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -2681,6 +2681,8 @@ void QDockAreaLayout::getGrid(QVector<QLayoutStruct> *_ver_struct_list,
             ver_struct_list[i].sizeHint
                 = qMax(ver_struct_list[i].sizeHint, ver_struct_list[i].minimumSize);
         }
+        if (have_central && ver_struct_list[0].empty && ver_struct_list[2].empty)
+            ver_struct_list[1].maximumSize = QWIDGETSIZE_MAX;
     }
 
     if (_hor_struct_list != 0) {
@@ -2740,6 +2742,9 @@ void QDockAreaLayout::getGrid(QVector<QLayoutStruct> *_ver_struct_list,
             hor_struct_list[i].sizeHint
                 = qMax(hor_struct_list[i].sizeHint, hor_struct_list[i].minimumSize);
         }
+        if (have_central && hor_struct_list[0].empty && hor_struct_list[2].empty)
+            hor_struct_list[1].maximumSize = QWIDGETSIZE_MAX;
+
     }
 }
 
diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index cab60f75ec..1808030639 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -3058,6 +3058,9 @@ void QMdiSubWindow::leaveEvent(QEvent * /*leaveEvent*/)
 
 /*!
     \reimp
+
+    \warning When maximizing or restoring a subwindow, the resulting call to this function
+    may have an invalid QResizeEvent::oldSize().
 */
 void QMdiSubWindow::resizeEvent(QResizeEvent *resizeEvent)
 {