QmlDesigner: Offset move/scale gizmo label in screen space

Offsetting in scene space resulted in label being inconsistent distance
away from the object, depending on zoom and angle.

Change-Id: Ief555de664c042bb1a5c93af0ee7e5a1c3e7ce0a
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

share/qtcreator/qml/qmlpuppet/mockfiles/EditView3D.qml

@@ -257,13 +257,12 @@ Window {
             id: gizmoLabel
             targetNode: moveGizmo.visible ? moveGizmo : scaleGizmo
             targetView: overlayView
-            offset: Qt.vector3d(0, 45, 0)
             visible: targetNode.dragging
 
             Rectangle {
                 color: "white"
                 x: -width / 2
-                y: -height
+                y: -height - 8
                 width: gizmoLabelText.width + 4
                 height: gizmoLabelText.height + 4
                 border.width: 1