Finally found the large dash code

mitterlib/ui/ui_pygtk.py

@@ -576,7 +576,7 @@ class Interface(object):
             read_status = ''
 
         if data.reposted_by:
-            markup = '<b>%s</b> <small>(%s -- <i>reposted by %s</i>)' \
+            markup = '<b>%s</b> <small>(%s &#8212; <i>reposted by %s</i>)' \
                     '</small>:%s\n%s\n<small>%s</small>' % \
                     (data.name, username, data.reposted_by, read_status,
                             message, time)