Improve qtquick controls page

Added more information for "Getting Started"
- Cleaned up some language
- Remove desktop specific
- Mention widget dependency
- Use QmlApplicationEngine in example

Change-Id: I0e5d4bef124ce4571c1b6fe780ee78b8231cbb32
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>

src/controls/doc/src/qtquickcontrols-index.qdoc

@@ -29,19 +29,16 @@
     \page qtquickcontrols-index.html
     \title Qt Quick Controls
 
-    \brief The Qt Quick Controls module provides a set of reusable Qt Quick UI components.
+    \brief The Qt Quick Controls module provides a set of UI controls for Qt Quick.
 
-    The Qt Quick Controls module provides a set of reusable UI components to create
-    classic desktop-style user interfaces using Qt Quick.
+    The Qt Quick Controls module provides a set of controls that can be used to
+    build complete interfaces in Qt Quick.
 
     The module is new in Qt 5.1 and requires \l{Qt Quick} 2.1.
 
-    \note \l{Qt Quick Layouts} can be used to arrange Qt Quick Controls in a user interface.
+    \image qtquickcontrols-example-gallery.png
 
-    \note The current focus is on desktop, but in the long term Qt Quick Controls
-    are expected to be supported on mobile platforms too.
-
-    \section1 Getting started
+    \section1 Getting Started
 
     The QML types can be imported into your application using the following import statement in your \c {.qml} file.
 
@@ -49,6 +46,47 @@
      import QtQuick.Controls 1.0
     \endcode
 
+    A basic example of a QML file that makes use of controls is shown here:
+
+    \code
+    import QtQuick.Controls 1.0
+
+    ApplicationWindow {
+        title: "My Application"
+
+        Button {
+            text: "Push Me"
+            anchors.centerIn: parent
+        }
+    }
+    \endcode
+
+    \section2 Setting Up Controls from C++
+
+    While we traditionally have used a QQuickView window to display QML files
+    in a C++ application, doing this means you can only set window properties from C++.
+
+    With Qt Quick Controls, declare an ApplicationWindow as the root item of your application and launch it by using the
+    QQmlApplicationEngine instead. This ensures that you can control top level window properties from QML.
+
+    A basic example of a source file that makes use of controls is shown here:
+
+    \code
+    #include <QApplication>
+    #include <QQmlApplicationEngine>
+
+    int main(int argc, char *argv[])
+    {
+        QApplication app(argc, argv);
+        QQmlApplicationEngine engine("main.qml");
+        return app.exec();
+    }
+    \endcode
+
+    \note We are using QApplication and not QGuiApplication in this example.
+    Though you can use QGuiApplication instead, doing this will eliminate platform-dependent styling.
+    This is because it is relying on the widget module to provide the native look and feel.
+
     \section1 Application Window
     Components used to describe the basic window properties of an application.
     \annotatedlist applicationwindow