QmlDesigner.PropertyEditor: fixing ButtonRow

We have to react to a change of checkedIndex

Change-Id: Icb2fd8efb236d6b2764ae901968f693f09c46d42
Reviewed-by: Marco Bubke <marco.bubke@digia.com>

share/qtcreator/qmldesigner/propertyEditorQmlSources/HelperWidgets/ButtonRow.qml

@@ -41,6 +41,10 @@ Row {
 
     property int checkedIndex: -1
 
+    onCheckedIndexChanged: {
+        __checkButton(checkedIndex)
+    }
+
     signal toggled (int index, bool checked)
 
     Component.onCompleted: {