Internally document QQuickApplicationWindow's item hierarchy

This changed after 83d90845527799c78366c2b89e9c14bc35e88695. It's not
documented anywhere and is difficult to follow when going only by the
code.

Task-number: QTBUG-136031
Pick-to: 6.9
Change-Id: Ia9a12191bb19d8dd23d142a78dbe573a4d2e3007
Reviewed-by: Tor Arne Vestbø <[email protected]>

1 files changed, 15 insertions, 3 deletions

diff --git a/src/quicktemplates/qquickapplicationwindow.cpp b/src/quicktemplates/qquickapplicationwindow.cpp
index 5f17a50b3c..932957eb44 100644
--- a/src/quicktemplates/qquickapplicationwindow.cpp
+++ b/src/quicktemplates/qquickapplicationwindow.cpp
@@ -817,9 +817,21 @@ void QQuickApplicationWindow::classBegin()
     QQuickWindowQmlImpl::classBegin();
     d->resolveFont();
 
-    // Create the control up front, rather than lazily, as we have
-    // to set the default padding before any user-bindings override
-    // them.
+    /*
+        Create the control up front, rather than lazily, as we have
+        to set the default padding before any user-bindings override
+        them.
+
+        The hierarchy is:
+
+            contentItem (QQuickRootItem)
+            ├── menuBar
+            ├── header
+            ├── control (QQuickControl)
+            │   └── control->contentItem() (QQuickContentItem)
+            ├── footer
+            └── background
+     */
     d->control = new QQuickControl(QQuickWindow::contentItem());
     d->control->setObjectName("ApplicationWindowContentControl");
 #if QT_CONFIG(quicktemplates2_hover)