[gnome-builder] editor: be extra careful about NULL in GtkEntry property bindings

[Christian Hergert <chergert src gnome org>]

commit 3aa040ba0d58145d01c1c3292e7ab94a219bffb9
Author: Christian Hergert <christian hergert me>
Date:   Mon Mar 23 16:12:43 2015 -0700

    editor: be extra careful about NULL in GtkEntry property bindings

 src/editor/gb-editor-frame.c |   20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)
---
diff --git a/src/editor/gb-editor-frame.c b/src/editor/gb-editor-frame.c
index 081615b..e6a9d21 100644
--- a/src/editor/gb-editor-frame.c
+++ b/src/editor/gb-editor-frame.c
@@ -182,6 +182,23 @@ search_text_transform_to (GBinding     *binding,
   return TRUE;
 }
 
+static gboolean
+search_text_transform_from (GBinding     *binding,
+                            const GValue *from_value,
+                            GValue       *to_value,
+                            gpointer      user_data)
+{
+  g_assert (from_value != NULL);
+  g_assert (to_value != NULL);
+
+  if (g_value_get_string (from_value) == NULL)
+    g_value_set_string (to_value, "");
+  else
+    g_value_copy (from_value, to_value);
+
+  return TRUE;
+}
+
 void
 gb_editor_frame_set_document (GbEditorFrame    *self,
                               GbEditorDocument *document)
@@ -209,7 +226,8 @@ gb_editor_frame_set_document (GbEditorFrame    *self,
   search_settings = gtk_source_search_context_get_settings (search_context);
   g_object_bind_property_full (self->search_entry, "text", search_settings, "search-text",
                                (G_BINDING_SYNC_CREATE | G_BINDING_BIDIRECTIONAL),
-                               search_text_transform_to, NULL, NULL, NULL);
+                               search_text_transform_to, search_text_transform_from,
+                               NULL, NULL);
   g_signal_connect_object (search_context,
                            "notify::occurrences-count",
                            G_CALLBACK (gb_editor_frame_on_search_occurrences_notify),