widgets/thread: treat multipart/alternative with one subpart as mixed

Some systems create multipart/alternative emails with just one subpart.
There is no point in drawing decorations for them, since there are no
other alternatives to switch to, so treat them as mixed.

1 files changed, 4 insertions, 1 deletions

diff --git a/alot/widgets/thread.py b/alot/widgets/thread.py
index 3da660a5..b6eb31d5 100644
--- a/alot/widgets/thread.py
+++ b/alot/widgets/thread.py
@@ -372,7 +372,10 @@ def _handle_multipart(mime_tree, alternative_pref):
             children.append(ch)
 
     if len(children) > 0:
-        if mime_tree.is_alternative:
+        # there exist some intelligence-challenged systems in the wild producing
+        # multipart/alternative with just a single alternative - treat those as
+        # mixed and so avoid displaying pointless decorations
+        if mime_tree.is_alternative and len(children) > 1:
             return _MultiAltWidget(children, mime_tree.children, alternative_pref)
         return _MultiMixedWidget(children)