[dia] ObjectChange::(apply|revert) second parameter can be NULL

[Hans Breuer <hans src gnome org>]

commit d106a40cfac0bf2401e587a6b827b4028c181479
Author: Hans Breuer <hans breuer org>
Date:   Fri Sep 10 15:38:42 2010 +0200

    ObjectChange::(apply|revert) second parameter can be NULL
    
    Don't rely assert on the (deprecated) object parameter being != NULL

 lib/element.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/element.c b/lib/element.c
index f45dc40..942f691 100644
--- a/lib/element.c
+++ b/lib/element.c
@@ -487,7 +487,7 @@ _element_change_swap (ObjectChange *self,
   Point tmppt;
   real  tmp;
 
-  g_assert(obj == &(ec->element->object));
+  g_assert(!obj || obj == &(ec->element->object));
 
   tmppt = ec->corner; ec->corner = elem->object.position; elem->object.position = tmppt;
   tmp = ec->width; ec->width = elem->width; elem->width = tmp;