[dia] Bug 614278 - Only remove the active layer on load of initial diagram

[Hans Breuer <hans src gnome org>]

commit 3e42f741f68260b31ae266aef49f6f1b0dc47f29
Author: Hans Breuer <hans breuer org>
Date:   Sun Jan 30 15:08:34 2011 +0100

    Bug 614278 - Only remove the active layer on load of initial diagram
    
    An important invariant of DiagramData::active_layer is it being always
    valid. As a result the initial object can not be created without a layer,
    but that layer gets replaced when laoding a diagram.
    Now with real load-into as in dropping another diagram/file into an
    existing one this would destroy part of the diagram to preserve. So the
    unusual side-effect of diagram_data_load() is restricted to the case
    described above.

 app/load_save.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/app/load_save.c b/app/load_save.c
index 4de4954..a2fe830 100644
--- a/app/load_save.c
+++ b/app/load_save.c
@@ -418,9 +418,11 @@ diagram_data_load(const char *filename, DiagramData *data, void* user_data)
   }
   
   /* Destroy the default layer: */
-  g_ptr_array_remove(data->layers, data->active_layer);
-  layer_destroy(data->active_layer);
-  
+  if (layer_object_count(data->active_layer) == 0) {
+    g_ptr_array_remove(data->layers, data->active_layer);
+    layer_destroy(data->active_layer);
+  }
+
   diagramdata = 
     find_node_named (doc->xmlRootNode->xmlChildrenNode, "diagramdata");