Implement base Compose screen

osu.Game/Screens/Edit/Editor.cs

@@ -14,6 +14,7 @@ using osu.Game.Screens.Edit.Components.Timelines.Summary;
 using OpenTK;
 using osu.Framework.Allocation;
 using osu.Game.Screens.Edit.Screens;
+using osu.Game.Screens.Edit.Screens.Compose;
 
 namespace osu.Game.Screens.Edit
 {
@@ -110,6 +111,9 @@ namespace osu.Game.Screens.Edit
 
             switch (mode)
             {
+                case EditorScreenMode.Compose:
+                    currentScreen = new Compose();
+                    break;
                 default:
                     currentScreen = new EditorScreen();
                     break;

osu.Game/Screens/Edit/Screens/Compose/Compose.cs

@@ -0,0 +1,42 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using OpenTK.Graphics;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Graphics;
+
+namespace osu.Game.Screens.Edit.Screens.Compose
+{
+    public class Compose : EditorScreen
+    {
+        public Compose()
+        {
+            Children = new[]
+            {
+                new Container
+                {
+                    Name = "Timeline",
+                    RelativeSizeAxes = Axes.X,
+                    Height = 110,
+                    Children = new Drawable[]
+                    {
+                        new Box
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            Colour = Color4.Black.Opacity(0.5f)
+                        },
+                        new Container
+                        {
+                            Name = "Content",
+                            RelativeSizeAxes = Axes.Both,
+                            Padding = new MarginPadding { Horizontal = 17, Vertical = 10 }
+                        }
+                    }
+                }
+            };
+        }
+    }
+}

osu.Game/osu.Game.csproj

@@ -619,6 +619,7 @@
     <Compile Include="Screens\Edit\Menus\EditorMenuItemSpacer.cs" />
     <Compile Include="Screens\Edit\Menus\ScreenSelectionTabControl.cs" />
     <Compile Include="Screens\Edit\Screens\EditorScreen.cs" />
+    <Compile Include="Screens\Edit\Screens\Compose\Compose.cs" />
     <Compile Include="Screens\Loader.cs" />
     <Compile Include="Screens\Menu\Button.cs" />
     <Compile Include="Screens\Menu\ButtonSystem.cs" />