Reading the pango docs, I found the proper way to escape special chars

mitterlib/ui/ui_pygtk.py

@@ -29,9 +29,10 @@ import re
 import urllib2
 import webbrowser
 
+from cgi import escape as html_escape
+
 from mitterlib.ui.helpers.image_helpers import find_image
 from mitterlib import htmlize
-
 from mitterlib.constants import gpl_3, version
 from mitterlib.ui.helpers import timesince
 
@@ -578,9 +579,7 @@ class Interface(object):
         time = timesince.timesince(data.message_time)
 
         # unescape escaped entities that pango is not okay with
-        message = re.sub(r'&', r'&', message)
+        message = html_escape(message)
-        message = re.sub(r'<', r'&lt;', message)
-        message = re.sub(r'>', r'&gt;', message)
 
         # highlight URLs
         mask = r'<span foreground="%s">\1</span>' % (