[gnome-builder] gstyle: fix GstyleSlidein with no overlay child

[Sébastien Lafargue <slafargue src gnome org>]

commit b0d7ef3c40ebc53475499810f9ad05b53bb0790d
Author: Sébastien Lafargue <slafargue gnome org>
Date:   Mon Dec 26 17:36:53 2016 +0100

    gstyle: fix GstyleSlidein with no overlay child
    
    in gstyle_slidein_realize we need to protect
    against creating the overlay window when
    there is no child yet.

 contrib/gstyle/gstyle-slidein.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/contrib/gstyle/gstyle-slidein.c b/contrib/gstyle/gstyle-slidein.c
index c66bb66..2638bb7 100644
--- a/contrib/gstyle/gstyle-slidein.c
+++ b/contrib/gstyle/gstyle-slidein.c
@@ -952,7 +952,7 @@ gstyle_slidein_realize (GtkWidget *widget)
   GTK_WIDGET_CLASS (gstyle_slidein_parent_class)->realize (widget);
   gtk_widget_set_realized (widget, TRUE);
 
-  if (self->overlay_window == NULL)
+  if (self->overlay_child != NULL && self->overlay_window == NULL)
     self->overlay_window = gstyle_slidein_create_child_window (self);
 }