[balsa/stop-using-gtkbox-child-properties: 5/10] source-viewer: Use container-add for a scrolled w

[Peter Bloomfield <peterb src gnome org>]

commit 3577f63ce7de38ae75db562a6ab97d3f7ae8566e
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Sun Jun 7 10:29:07 2020 -0400

    source-viewer: Use container-add for a scrolled w

 libbalsa/source-viewer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/libbalsa/source-viewer.c b/libbalsa/source-viewer.c
index 2a51df35d..946cfe795 100644
--- a/libbalsa/source-viewer.c
+++ b/libbalsa/source-viewer.c
@@ -245,7 +245,8 @@ libbalsa_show_message_source(GtkApplication  * application,
 
     gtk_widget_set_vexpand(interior, TRUE);
     gtk_widget_set_valign(interior, GTK_ALIGN_FILL);
-    gtk_box_pack_start(GTK_BOX(vbox), interior, FALSE, FALSE, 0);
+    g_object_set(interior, "margin", 2, NULL);
+    gtk_container_add(GTK_CONTAINER(vbox), interior);
     gtk_container_add(GTK_CONTAINER(window), vbox);
 
     lsvi = g_new(LibBalsaSourceViewerInfo, 1);