Fixed a crash with input methods

The inputContext's focusWidget was not reset when disabling input
methods.
Thanks to Benjamin P.

Task-number: 257832
Reviewed-by: Denis

3 files changed, 18 insertions, 6 deletions

diff --git a/src/gui/kernel/qapplication.cpp b/src/gui/kernel/qapplication.cpp
index c6af728..114ebb2 100644
--- a/src/gui/kernel/qapplication.cpp
+++ b/src/gui/kernel/qapplication.cpp
@@ -126,7 +126,7 @@ int QApplicationPrivate::app_compile_version = 0x040000; //we don't know exactly
 QApplication::Type qt_appType=QApplication::Tty;
 QApplicationPrivate *QApplicationPrivate::self = 0;
 
-QInputContext *QApplicationPrivate::inputContext;
+QInputContext *QApplicationPrivate::inputContext = 0;
 
 bool QApplicationPrivate::quitOnLastWindowClosed = true;
 
diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 9d40b00..fb9084e 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -9879,11 +9879,8 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
             QInputContextPrivate::updateImeStatus(this, true);
 #endif
         QInputContext *ic = d->ic;
-        if (!ic) {
-            // implicitly create input context only if we have a focus
-            if (hasFocus())
-                ic = d->inputContext();
-        }
+        if (!ic && (!on || hasFocus()))
+            ic = d->inputContext();
         if (ic) {
             if (on && hasFocus() && ic->focusWidget() != this) {
                 ic->setFocusWidget(this);
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index 7b68732..1db6eb2 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -350,6 +350,7 @@ private slots:
 #endif
     void updateOnDestroyedSignal();
     void toplevelLineEditFocus();
+    void inputFocus_task257832();
 
 private:
     bool ensureScreenSize(int width, int height);
@@ -8965,5 +8966,19 @@ void tst_QWidget::toplevelLineEditFocus()
     QCOMPARE(QApplication::focusWidget(), &w);
 }
 
+void tst_QWidget::inputFocus_task257832()
+{
+      QLineEdit *widget = new QLineEdit;
+      QInputContext *context = widget->inputContext();
+      if (!context)
+            QSKIP("No input context", SkipSingle);
+      widget->setFocus();
+      context->setFocusWidget(widget);
+      QCOMPARE(context->focusWidget(), widget);
+      widget->setReadOnly(true);
+      QVERIFY(!context->focusWidget());
+      delete widget;
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"