[dia] Don't try to set NULL as filename

[Hans Breuer <hans src gnome org>]

commit ffc377ef7f3d90159532d01c067a15da9034b9a2
Author: Hans Breuer <hans breuer org>
Date:   Sun Sep 12 13:25:36 2010 +0200

    Don't try to set NULL as filename

 lib/prop_text.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/lib/prop_text.c b/lib/prop_text.c
index 248dc32..4540c7a 100644
--- a/lib/prop_text.c
+++ b/lib/prop_text.c
@@ -166,7 +166,8 @@ fileprop_get_widget(StringProperty *prop, PropDialog *dialog)
 static void 
 fileprop_reset_widget(StringProperty *prop, GtkWidget *widget)
 {
-  dia_file_selector_set_file(DIAFILESELECTOR(widget),prop->string_data);
+  if (prop->string_data)
+    dia_file_selector_set_file(DIAFILESELECTOR(widget),prop->string_data);
 }
 
 static void