inspector: Avoid a critical

If a layout manager does not have layout children,
quietly hide the layout page.

diff --git a/gtk/inspector/prop-list.c b/gtk/inspector/prop-list.c
index 60096bbc659d073255396013de9dc369b80fc6ca..97edae10fc0d3c88b25116a1f375d9115ddfc3cb 100644 (file)
--- a/gtk/inspector/prop-list.c
+++ b/gtk/inspector/prop-list.c
@@ -528,6 +528,9 @@ gtk_inspector_prop_list_set_layout_child (GtkInspectorPropList *pl,
   if (!layout_manager)
     return;
 
+  if (GTK_LAYOUT_MANAGER_GET_CLASS (layout_manager)->layout_child_type == G_TYPE_INVALID)
+    return;
+
   layout_child = gtk_layout_manager_get_layout_child (layout_manager, GTK_WIDGET (object));
   if (!layout_child)
     return;