Add in-game chat display, along with a global hotkey handling method.

osu.Game/Input/GlobalHotkeys.cs

@@ -0,0 +1,21 @@
+//Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
+//Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using osu.Framework.Graphics;
+using osu.Framework.Input;
+
+namespace osu.Game.Input
+{
+    public class GlobalHotkeys : Drawable
+    {
+        public Func<InputState, KeyDownEventArgs, bool> Handler;
+
+        public override bool HandleInput => true;
+
+        protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
+        {
+            return Handler(state, args);
+        }
+    }
+}