[balsa] balsa-message: Unref the BalsaMimeWidget

[Peter Bloomfield <peterb src gnome org>]

commit 8822d378d18e32127c061505e614fba6ee5cd6ba
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Thu Feb 14 15:52:51 2019 -0500

    balsa-message: Unref the BalsaMimeWidget

 src/balsa-message.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/src/balsa-message.c b/src/balsa-message.c
index b95d3cde0..67a57f305 100644
--- a/src/balsa-message.c
+++ b/src/balsa-message.c
@@ -856,6 +856,11 @@ balsa_message_destroy(GObject * object)
     }
 #endif                          /* HAVE_HTML_WIDGET */
 
+    if (bm->bm_widget) {
+       g_object_unref(bm->bm_widget);
+       bm->bm_widget = NULL;
+    }
+
     if (G_OBJECT_CLASS(parent_class)->dispose)
         (*G_OBJECT_CLASS(parent_class)->dispose) (object);
 }