--- a/editors/Viewer.py	Mon Sep 10 03:14:09 2012 +0200
+++ b/editors/Viewer.py	Tue Sep 11 01:06:59 2012 +0200
@@ -1783,7 +1783,7 @@
             self.SelectedElement.SetHighlighted(True)
             
             if self.Debug:
-                if self.IsBlock(self.SelectedElement):
+                if isinstance(self.SelectedElement, FBD_Block):
                     instance_type = self.SelectedElement.GetType()
                     pou_type = {
                         "program": ITEM_PROGRAM,