view/thread.rs: fix expanded_hash argument off by one error

When calling ThreadView::new with an envelope hash, Some(expanded_hash),
in the arguments, when translating it to a cursor position (usize) it
was mistakenly subtracted with 1 resulting in the wrong thread entry
showing up as expanded.

src/components/mail/listing.rs

@@ -103,16 +103,27 @@ impl<T> RowsState<T> {
         entry_strings: EntryStrings,
     ) {
         env_hashes.dedup();
+        env_hashes.retain(|h| !self.all_envelopes.contains(h));
+        if env_hashes.is_empty() {
+            return;
+        }
         let index = self.entries.len();
-        self.thread_order.insert(thread, index);
-        self.all_threads.insert(thread);
         for &env_hash in &env_hashes {
             self.selection.insert(env_hash, false);
             self.env_to_thread.insert(env_hash, thread);
             self.env_order.insert(env_hash, index);
             self.all_envelopes.insert(env_hash);
         }
-        self.thread_to_env.insert(thread, env_hashes);
+        if !self.all_threads.contains(&thread) {
+            self.thread_order.insert(thread, index);
+            self.all_threads.insert(thread);
+            self.thread_to_env.insert(thread, env_hashes);
+        } else {
+            self.thread_to_env
+                .entry(thread)
+                .or_default()
+                .extend_from_slice(&env_hashes);
+        }
         self.entries.push((metadata, entry_strings));
     }
 

src/components/mail/listing/thread.rs

@@ -782,12 +782,7 @@ impl ThreadListing {
     }
 
     fn get_env_under_cursor(&self, cursor: usize) -> Option<EnvelopeHash> {
-        self.rows
-            .env_order
-            .iter()
-            .find(|(_, &r)| r == cursor)
-            .map(|v| v.0)
-            .cloned()
+        self.rows.entries.get(cursor).map(|v| (v.0).1)
     }
 
     fn make_entry_string(&self, e: &Envelope, context: &Context) -> EntryStrings {

src/components/mail/view/thread.rs

@@ -231,7 +231,7 @@ impl ThreadView {
             };
             match expanded_hash {
                 Some(expanded_hash) if expanded_hash == entry.msg_hash => {
-                    self.new_expanded_pos = self.entries.len().saturating_sub(1);
+                    self.new_expanded_pos = self.entries.len();
                     self.expanded_pos = self.new_expanded_pos + 1;
                 }
                 _ => {}