Doc: Mention that calling parent class event() is important

If you don't deleteLater and more won't work

Change-Id: I47cbb24f8e22a7f269a0297410e4163878819f82
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/doc/snippets/code/src_corelib_kernel_qobject.cpp

@@ -486,6 +486,33 @@ QObject::connect(socket, &QTcpSocket::connected, this, [=] () {
     }, Qt::AutoConnection);
 //! [51]
 
+//! [52]
+class MyClass : public QWidget
+{
+    Q_OBJECT
+
+public:
+    MyClass(QWidget *parent = 0);
+    ~MyClass();
+
+    bool event(QEvent* ev)
+    {
+        if (ev->type() == QEvent::PolishRequest) {
+            // overwrite handling of PolishRequest if any
+            doThings();
+            return true;
+        } else  if (ev->type() == QEvent::Show) {
+            // complement handling of Show if any
+            doThings2();
+            QWidget::event(ev);
+            return true;
+        }
+        // Make sure the rest of events are handled
+        return QWidget::event(ev);
+    }
+};
+//! [52]
+
 //! [meta data]
 //: This is a comment for the translator.
 //= qtn_foo_bar

src/corelib/kernel/qobject.cpp

@@ -1219,6 +1219,13 @@ void QObject::setObjectName(const QString &name)
     The event() function can be reimplemented to customize the
     behavior of an object.
 
+    Make sure you call the parent event class implementation
+    for all the events you did not handle.
+
+    Example:
+
+    \snippet code/src_corelib_kernel_qobject.cpp 52
+
     \sa installEventFilter(), timerEvent(), QCoreApplication::sendEvent(),
     QCoreApplication::postEvent()
 */