The QDialog::showFullScreen() does not work on OS X system.

diff --git a/examples/widgets/desktop/systray/window.cpp b/examples/widgets/desk
index 0ef5ddb..bb31124 100644
--- a/examples/widgets/desktop/systray/window.cpp
+++ b/examples/widgets/desktop/systray/window.cpp
@@ -92,7 +92,7 @@ Window::Window()
 void Window::setVisible(bool visible)
 {
     minimizeAction->setEnabled(visible);
-    maximizeAction->setEnabled(!isMaximized());
+    maximizeAction->setEnabled(!isFullScreen());
     restoreAction->setEnabled(isMaximized() || !visible);
     QDialog::setVisible(visible);
 }
@@ -247,7 +249,7 @@ void Window::createActions()
     connect(minimizeAction, SIGNAL(triggered()), this, SLOT(hide()));

     maximizeAction = new QAction(tr("Ma&ximize"), this);
-    connect(maximizeAction, SIGNAL(triggered()), this, SLOT(showMaximized()));
+    connect(maximizeAction, SIGNAL(triggered()), this, SLOT(showFullScreen()));

     restoreAction = new QAction(tr("&Restore"), this);
     connect(restoreAction, SIGNAL(triggered()), this, SLOT(showNormal()));