diff -r d9ed42e44a50 -r 18cd1357e8d3 dialogs/BlockPreviewDialog.py
--- a/dialogs/BlockPreviewDialog.py	Wed Jun 12 11:32:44 2013 +0200
+++ b/dialogs/BlockPreviewDialog.py	Wed Jun 12 22:23:57 2013 +0200
@@ -269,21 +269,24 @@
         height = max(self.MinElementSize[1], min_height)
         self.Element.SetSize(width, height)
         
+        # Get element bounding box to center in preview
+        bbox = self.Element.GetBoundingBox()
+        
         # Get Preview panel size
         client_size = self.Preview.GetClientSize()
         
         # If graphic element is too big to be displayed in preview panel,
         # calculate preview panel scale so that graphic element fit inside
-        scale = (max(float(width) / client_size.width, 
-                     float(height) / client_size.height) * 1.2
-                 if width * 1.2 > client_size.width or 
-                    height * 1.2 > client_size.height
+        scale = (max(float(bbox.width) / client_size.width, 
+                     float(bbox.height) / client_size.height) * 1.2
+                 if bbox.width * 1.1 > client_size.width or 
+                    bbox.height * 1.1 > client_size.height
                  else 1.0)
         dc.SetUserScale(1.0 / scale, 1.0 / scale)
         
         # Center graphic element in preview panel
-        x = int(client_size.width * scale - width) / 2
-        y = int(client_size.height * scale - height) / 2
+        x = int(client_size.width * scale - bbox.width) / 2
+        y = int(client_size.height * scale - bbox.height) / 2
         self.Element.SetPosition(x, y)
         
         # Draw graphic element