From 44dc3f494c24c3591b466d43cec5203b22ff8e2b Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Fri, 12 Mar 2021 17:56:13 +1000
Subject: [PATCH] avoid hanging UI when undoing in browse screen

---
 pylib/anki/collection.py |  2 ++
 qt/aqt/browser.py        | 12 +++++++++++-
 qt/aqt/main.py           | 10 ++++++++--
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/pylib/anki/collection.py b/pylib/anki/collection.py
index 2bb63b7c1..3cf5a3ea6 100644
--- a/pylib/anki/collection.py
+++ b/pylib/anki/collection.py
@@ -72,8 +72,10 @@ class Checkpoint:
 class BackendUndo:
     name: str
 
+
 UndoResult = Union[None, BackendUndo, Checkpoint, ReviewUndo]
 
+
 class Collection:
     sched: Union[V1Scheduler, V2Scheduler]
 
diff --git a/qt/aqt/browser.py b/qt/aqt/browser.py
index 93e9330c1..0ff9db88f 100644
--- a/qt/aqt/browser.py
+++ b/qt/aqt/browser.py
@@ -518,7 +518,7 @@ class Browser(QMainWindow):
         # actions
         f = self.form
         # edit
-        qconnect(f.actionUndo.triggered, self.mw.onUndo)
+        qconnect(f.actionUndo.triggered, self.undo)
         qconnect(f.actionInvertSelection.triggered, self.invertSelection)
         qconnect(f.actionSelectNotes.triggered, self.selectNotes)
         if not isMac:
@@ -1498,6 +1498,16 @@ where id in %s"""
     def on_tag_list_update(self) -> None:
         self.sidebar.refresh()
 
+    # Undo
+    ######################################################################
+
+    def undo(self) -> None:
+        # need to make sure we don't hang the UI by redrawing the card list
+        # during the long-running op. mw.undo will take care of the progress
+        # dialog
+        self.setUpdatesEnabled(False)
+        self.mw.undo(lambda _: self.setUpdatesEnabled(True))
+
     def onUndoState(self, on: bool) -> None:
         self.form.actionUndo.setEnabled(on)
         if on:
diff --git a/qt/aqt/main.py b/qt/aqt/main.py
index 2b061dbba..eef4e99d0 100644
--- a/qt/aqt/main.py
+++ b/qt/aqt/main.py
@@ -27,8 +27,14 @@ import aqt.toolbar
 import aqt.webview
 from anki import hooks
 from anki._backend import RustBackend as _RustBackend
-from anki.collection import BackendUndo, Checkpoint, Collection, Config, \
-    ReviewUndo, UndoResult
+from anki.collection import (
+    BackendUndo,
+    Checkpoint,
+    Collection,
+    Config,
+    ReviewUndo,
+    UndoResult,
+)
 from anki.decks import Deck
 from anki.hooks import runHook
 from anki.sound import AVTag, SoundOrVideoTag