QMdiArea: Store focus widget when new QMdiSubWindow is added.

Introduce function QMdiSubWindowPrivate::storeFocusWidget()
to store focus widget and call this when de-activating a
sub window. Change restoreFocus() to return a bool and call
it from QMdiSubWindowPrivate::setActive().

Task-number: QTBUG-38378
Change-Id: I18dbe66ce85213ca5b4907b5a09126544415351a
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/widgets/widgets/qmdisubwindow.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -1321,6 +1321,14 @@ void QMdiSubWindowPrivate::setNormalMode()
     updateMask();
 }
 
+inline void QMdiSubWindowPrivate::storeFocusWidget()
+{
+    if (QWidget *focus = QApplication::focusWidget()) {
+        if (!restoreFocusWidget && q_func()->isAncestorOf(focus))
+            restoreFocusWidget = focus;
+    }
+}
+
 /*!
     \internal
 */
@@ -1333,8 +1341,7 @@ void QMdiSubWindowPrivate::setMaximizeMode()
     isShadeMode = false;
     isMaximizeMode = true;
 
-    if (!restoreFocusWidget && q->isAncestorOf(QApplication::focusWidget()))
-        restoreFocusWidget = QApplication::focusWidget();
+    storeFocusWidget();
 
 #ifndef QT_NO_SIZEGRIP
     setSizeGripVisible(false);
@@ -1436,6 +1443,7 @@ void QMdiSubWindowPrivate::setActive(bool activate, bool changeFocus)
         Qt::WindowStates oldWindowState = q->windowState();
         q->overrideWindowState(q->windowState() & ~Qt::WindowActive);
         if (changeFocus) {
+            storeFocusWidget();
             QWidget *focusWidget = QApplication::focusWidget();
             if (focusWidget && (focusWidget == q || q->isAncestorOf(focusWidget)))
                 focusWidget->clearFocus();
@@ -2026,6 +2034,9 @@ void QMdiSubWindowPrivate::setFocusWidget()
         return;
     }
 
+    if (!(q->windowState() & Qt::WindowMinimized) && restoreFocus())
+        return;
+
     if (QWidget *focusWidget = baseWidget->focusWidget()) {
         if (!focusWidget->hasFocus() && q->isAncestorOf(focusWidget)
                 && focusWidget->isVisible() && !q->isMinimized()
@@ -2048,16 +2059,19 @@ void QMdiSubWindowPrivate::setFocusWidget()
         q->setFocus();
 }
 
-void QMdiSubWindowPrivate::restoreFocus()
+bool QMdiSubWindowPrivate::restoreFocus()
 {
-    if (!restoreFocusWidget)
-        return;
-    if (!restoreFocusWidget->hasFocus() && q_func()->isAncestorOf(restoreFocusWidget)
-            && restoreFocusWidget->isVisible()
-            && restoreFocusWidget->focusPolicy() != Qt::NoFocus) {
-        restoreFocusWidget->setFocus();
+    if (restoreFocusWidget.isNull())
+        return false;
+    QWidget *candidate = restoreFocusWidget;
+    restoreFocusWidget.clear();
+    if (!candidate->hasFocus() && q_func()->isAncestorOf(candidate)
+        && candidate->isVisible()
+        && candidate->focusPolicy() != Qt::NoFocus) {
+        candidate->setFocus();
+        return true;
     }
-    restoreFocusWidget = 0;
+    return candidate->hasFocus();
 }
 
 /*!
@@ -2605,9 +2619,7 @@ void QMdiSubWindow::showShaded()
 
     d->isMaximizeMode = false;
 
-    QWidget *currentFocusWidget = QApplication::focusWidget();
-    if (!d->restoreFocusWidget && isAncestorOf(currentFocusWidget))
-        d->restoreFocusWidget = currentFocusWidget;
+    d->storeFocusWidget();
 
     if (!d->isShadeRequestFromMinimizeMode) {
         d->isShadeMode = true;
@@ -2621,7 +2633,7 @@ void QMdiSubWindow::showShaded()
     // showMinimized() will reset Qt::WindowActive, which makes sense
     // for top level widgets, but in MDI it makes sense to have an
     // active window which is minimized.
-    if (hasFocus() || isAncestorOf(currentFocusWidget))
+    if (hasFocus() || isAncestorOf(QApplication::focusWidget()))
         d->ensureWindowState(Qt::WindowActive);
 
 #ifndef QT_NO_SIZEGRIP

src/widgets/widgets/qmdisubwindow_p.h

@@ -266,7 +266,8 @@ public:
     QPalette desktopPalette() const;
     void updateActions();
     void setFocusWidget();
-    void restoreFocus();
+    bool restoreFocus();
+    void storeFocusWidget();
     void setWindowFlags(Qt::WindowFlags windowFlags);
     void setVisible(WindowStateAction, bool visible = true);
 #ifndef QT_NO_ACTION

tests/auto/widgets/widgets/qmdisubwindow/tst_qmdisubwindow.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the test suite of the Qt Toolkit.
@@ -58,6 +58,7 @@
 #include <QStyle>
 #include <QStyleOptionTitleBar>
 #include <QPushButton>
+#include <QScreen>
 #include <QSizeGrip>
 
 #include "../../../qtest-config.h"
@@ -182,6 +183,7 @@ private slots:
     void mouseDoubleClick();
     void setSystemMenu();
     void restoreFocus();
+    void restoreFocusOverCreation();
     void changeFocusWithTab();
     void closeEvent();
     void setWindowTitle();
@@ -1126,6 +1128,7 @@ void tst_QMdiSubWindow::restoreFocus()
     expectedFocusWindow->showMinimized();
     qApp->processEvents();
     QVERIFY(expectedFocusWindow->isMinimized());
+    qDebug() << expectedFocusWindow<< qApp->focusWidget();
     QCOMPARE(qApp->focusWidget(), static_cast<QWidget *>(expectedFocusWindow));
 
     // Minimized -> normal
@@ -1178,6 +1181,48 @@ void tst_QMdiSubWindow::restoreFocus()
     QCOMPARE(qApp->focusWidget(), static_cast<QWidget *>(expectedFocusWindow));
 }
 
+class MultiWidget : public QWidget {
+public:
+    explicit MultiWidget(QWidget *parent = 0) : QWidget(parent)
+        , m_lineEdit1(new QLineEdit(this)), m_lineEdit2(new QLineEdit(this))
+    {
+        QVBoxLayout *lt = new QVBoxLayout(this);
+        lt->addWidget(m_lineEdit1);
+        lt->addWidget(m_lineEdit2);
+    }
+
+    QLineEdit *m_lineEdit1;
+    QLineEdit *m_lineEdit2;
+};
+
+void tst_QMdiSubWindow::restoreFocusOverCreation()
+{
+    // QTBUG-38378, verify that the focus child of a subwindow
+    // is not "forgotten" when adding yet another subwindow.
+    QMdiArea mdiArea;
+    mdiArea.resize(800, 800);
+    mdiArea.move(QGuiApplication::primaryScreen()->availableGeometry().center() - QPoint(400, 400));
+    mdiArea.setWindowTitle(QStringLiteral("restoreFocusOverCreation"));
+
+    MultiWidget *subWidget1 = new MultiWidget;
+    MultiWidget *subWidget2 = new MultiWidget;
+
+    QMdiSubWindow *subWindow1 = mdiArea.addSubWindow(subWidget1);
+    subWidget1->m_lineEdit2->setFocus();
+    subWindow1->show();
+    mdiArea.show();
+    QApplication::setActiveWindow(&mdiArea);
+    QVERIFY(QTest::qWaitForWindowActive(&mdiArea));
+    QCOMPARE(QApplication::focusWidget(), subWidget1->m_lineEdit2);
+
+    QMdiSubWindow *subWindow2 = mdiArea.addSubWindow(subWidget2);
+    subWindow2->show();
+    QTRY_COMPARE(QApplication::focusWidget(), subWidget2->m_lineEdit1);
+
+    mdiArea.setActiveSubWindow(subWindow1);
+    QTRY_COMPARE(QApplication::focusWidget(), subWidget1->m_lineEdit2);
+}
+
 void tst_QMdiSubWindow::changeFocusWithTab()
 {
     QWidget *widget = new QWidget;