ui: add triptych thread mailing view

This mail list view shows one entry per thread just like CompactListing,
but the entry is slightly bigger just like in some GUIs, and when the
thread is opened the view becomes 3 columned:

+--+-------+----+
|~~|-------|~~~ |
|~~|-------|~~  |
|  |-------|    |
|  |-------|~~~ |
+--+-------+----+

This is meant to be used with bigger terminal sizes

1 files changed, 4 insertions, 1 deletions

diff --git a/ui/src/conf.rs b/ui/src/conf.rs
index 289781d4..09c8decf 100644
--- a/ui/src/conf.rs
+++ b/ui/src/conf.rs
@@ -400,6 +400,7 @@ pub enum IndexStyle {
     Plain,
     Threaded,
     Compact,
+    Conversations,
 }
 
 impl Default for IndexStyle {
@@ -481,7 +482,8 @@ impl<'de> Deserialize<'de> for IndexStyle {
             "Plain" | "plain" => Ok(IndexStyle::Plain),
             "Threaded" | "threaded" => Ok(IndexStyle::Threaded),
             "Compact" | "compact" => Ok(IndexStyle::Compact),
-            _ => Err(de::Error::custom("invalid `index` value")),
+            "Conversations" | "conversations" => Ok(IndexStyle::Conversations),
+            _ => Err(de::Error::custom("invalid `index_style` value")),
         }
     }
 }
@@ -495,6 +497,7 @@ impl Serialize for IndexStyle {
             IndexStyle::Plain => serializer.serialize_str("plain"),
             IndexStyle::Threaded => serializer.serialize_str("threaded"),
             IndexStyle::Compact => serializer.serialize_str("compact"),
+            IndexStyle::Conversations => serializer.serialize_str("conversations"),
         }
     }
 }