Document how to position a popup in the center of the window

This was already in Overlay's docs, but not Popup's, so this
patch moves the example to a .qdocinc and includes it in both places,
creating a new Popup Positioning section in the process.

Change-Id: I8e8438919fd849a8466b3a28133d22bb45f7dc19
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/imports/controls/doc/src/includes/qquickoverlay-popup-parent.qdocinc b/src/imports/controls/doc/src/includes/qquickoverlay-popup-parent.qdocinc
new file mode 100644
index 00000000..7ad8a003
--- /dev/null
+++ b/src/imports/controls/doc/src/includes/qquickoverlay-popup-parent.qdocinc
@@ -0,0 +1,20 @@
+The following example uses the attached \l {Overlay::overlay}{Overlay.overlay}
+property to position a popup in the center of the window, despite the position
+of the button that opens the popup:
+
+\code
+Button {
+    onClicked: popup.open()
+
+    Popup {
+        id: popup
+
+        parent: Overlay.overlay
+
+        x: (parent.width - width) / 2
+        y: (parent.height - height) / 2
+        width: 100
+        height: 100
+    }
+}
+\endcode