Added warning

osu.Game/Screens/Edit/BookmarkResetDialog.cs

@@ -0,0 +1,26 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Game.Overlays.Dialog;
+
+namespace osu.Game.Screens.Edit
+{
+    public partial class BookmarkResetDialog : DeletionDialog
+    {
+        private readonly EditorBeatmap editor;
+
+        public BookmarkResetDialog(EditorBeatmap editorBeatmap)
+        {
+            editor = editorBeatmap;
+            BodyText = "All Bookmarks";
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            DangerousAction = () => editor.Bookmarks.Clear();
+        }
+    }
+}
+

osu.Game/Screens/Edit/Editor.cs

@@ -8,6 +8,7 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using DiffPlex.Model;
 using JetBrains.Annotations;
 using osu.Framework;
 using osu.Framework.Allocation;
@@ -450,7 +451,7 @@ private void load(OsuConfigManager config)
                                                     {
                                                         Hotkey = new Hotkey(GlobalAction.EditorSeekToNextBookmark)
                                                     },
-                                                    new EditorMenuItem(EditorStrings.ResetBookmarks, MenuItemType.Destructive, () => editorBeatmap.Bookmarks.Clear())
+                                                    new EditorMenuItem(EditorStrings.ResetBookmarks, MenuItemType.Destructive, () => dialogOverlay?.Push(new BookmarkResetDialog(editorBeatmap)))
                                                 }
                                             }
                                         }