fix: end undo groups, enter tree mode after undoing

src/engine/doc.rs

@@ -197,6 +197,10 @@ impl UndoGroup {
         }
 
         jump_to(s, cursor, self.restore_loc);
+        // Always end in tree mode, so that undoing can't unexpectedly enter text mode.
+        if let Some(new_cursor) = cursor.exit_text() {
+            *cursor = new_cursor;
+        }
         UndoGroup::new(redo_restore_loc.bug(), redos)
     }
 

src/keymap/layer.rs

@@ -240,6 +240,10 @@ impl LayerManager {
         }
     }
 
+    pub fn has_open_menu(&self) -> bool {
+        self.active_menu.is_some()
+    }
+
     /*********
      * Input *
      *********/

src/runtime.rs

@@ -312,7 +312,14 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
         };
         match self.layers.lookup_key(mode, doc_name, key) {
             None => Ok(None),
-            Some(KeyLookupResult::KeyProg(key_prog)) => Ok(Some(key_prog)),
+            Some(KeyLookupResult::KeyProg(key_prog)) => {
+                // Each keypress in tree mode should be a separate undo group, but multiple text
+                // edits (and multiple edits made in a menu) should be grouped together.
+                if mode != Mode::Text && !self.layers.has_open_menu() {
+                    let _ = self.engine.end_undo_group();
+                }
+                Ok(Some(key_prog))
+            }
             Some(KeyLookupResult::Redisplay) => {
                 self.display()?;
                 Ok(None)