From 4ffdffb598cc66b08169f43ebd1f1560592b058b Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Sat, 20 Apr 2019 16:20:03 +0100
Subject: [PATCH] Fix scrolling to selected row in collapsed mode

---
 src/devtools/store.js                        | 15 +++++++++++++++
 src/devtools/views/Components/TreeContext.js | 14 ++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/devtools/store.js b/src/devtools/store.js
index 048568d5bb..ff9129cb29 100644
--- a/src/devtools/store.js
+++ b/src/devtools/store.js
@@ -429,6 +429,21 @@ export default class Store extends EventEmitter {
     return null;
   }
 
+  isInsideCollapsedSubTree(id: number): boolean {
+    let current = this._idToElement.get(id);
+    while (current != null) {
+      if (current.parentID === 0) {
+        return false;
+      } else {
+        current = this._idToElement.get(current.parentID);
+        if (current != null && current.isCollapsed) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
   startProfiling(): void {
     this._bridge.send('startProfiling');
 
diff --git a/src/devtools/views/Components/TreeContext.js b/src/devtools/views/Components/TreeContext.js
index f66ad3e46e..bd295c920e 100644
--- a/src/devtools/views/Components/TreeContext.js
+++ b/src/devtools/views/Components/TreeContext.js
@@ -596,6 +596,20 @@ function TreeContextController({ children, viewElementSource }: Props) {
           state = reduceTreeState(store, state, action);
           state = reduceSearchState(store, state, action);
           state = reduceOwnersState(store, state, action);
+
+          // If the selected ID is in a collapsed subtree, reset the selected index to null.
+          // We'll know the correct index after the layout effect will toggle the tree,
+          // and the store tree is mutated to account for that.
+          if (
+            state.selectedElementID !== null &&
+            store.isInsideCollapsedSubTree(state.selectedElementID)
+          ) {
+            return {
+              ...state,
+              selectedElementIndex: null,
+            };
+          }
+
           return state;
         default:
           throw new Error(`Unrecognized action "${type}"`);