When view closes, focus on previous view

helix-view/src/tree.rs

@@ -219,7 +219,7 @@ impl Tree {
 
         if self.focus == index {
             // focus on something else
-            self.focus_next();
+            self.focus_prev();
         }
 
         stack.push(index);
@@ -521,6 +521,24 @@ impl Tree {
         Some(child_id)
     }
 
+    pub fn focus_prev(&mut self) {
+        let pos = self.traverse().position(|(id, _view)| id == self.focus);
+
+        if let Some(pos) = pos {
+            if pos > 0 {
+                match self.traverse().nth(pos - 1) {
+                    Some((id, _view)) => self.focus = id,
+                    None => {
+                        let (key, _) = self.traverse().next().unwrap();
+                        self.focus = key;
+                    }
+                }
+            } else {
+                self.focus_next();
+            }
+        }
+    }
+
     pub fn focus_next(&mut self) {
         // This function is very dumb, but that's because we don't store any parent links.
         // (we'd be able to go parent.next_sibling() recursively until we find something)