Implement a hold-to-confirm screen when exiting game using escape key

osu.Game/Screens/Menu/ExitConfirmOverlay.cs

@@ -0,0 +1,34 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Framework.Input;
+using osu.Game.Overlays;
+using OpenTK.Input;
+
+namespace osu.Game.Screens.Menu
+{
+    public class ExitConfirmOverlay : HoldToConfirmOverlay
+    {
+        protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
+        {
+            if (args.Key == Key.Escape && !args.Repeat)
+            {
+                BeginConfirm();
+                return true;
+            }
+
+            return base.OnKeyDown(state, args);
+        }
+
+        protected override bool OnKeyUp(InputState state, KeyUpEventArgs args)
+        {
+            if (args.Key == Key.Escape)
+            {
+                AbortConfirm();
+                return true;
+            }
+
+            return base.OnKeyUp(state, args);
+        }
+    }
+}