[gtk+] inspector: Avoid crash in magnifier

[Matthias Clasen <matthiasc src gnome org>]

commit dc407dbc8fc09bf3c41cb88eb1b90c7640097dfe
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Feb 8 09:34:24 2016 +0100

    inspector: Avoid crash in magnifier
    
    We can't use gtk_widget_draw on widgets that are not allocated.

 gtk/inspector/magnifier.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/inspector/magnifier.c b/gtk/inspector/magnifier.c
index c7b4a5b..5e6893e 100644
--- a/gtk/inspector/magnifier.c
+++ b/gtk/inspector/magnifier.c
@@ -49,7 +49,7 @@ gtk_inspector_magnifier_set_object (GtkInspectorMagnifier *sl,
 
   sl->priv->object = NULL;
 
-  if (!GTK_IS_WIDGET (object))
+  if (!GTK_IS_WIDGET (object) || !gtk_widget_is_visible (GTK_WIDGET (object)))
     {
       gtk_widget_hide (GTK_WIDGET (sl));
       _gtk_magnifier_set_inspected (GTK_MAGNIFIER (sl->priv->magnifier), NULL);