add basic variant of menu and context menu

osu.Framework.Tests/Visual/UserInterface/TestCaseContextMenu.cs

···
 // Copyright (c) ppy Pty Ltd <[e-mail]>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
+using System.Collections.Generic;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Cursor;
···
 
         private readonly ContextMenuBox movingBox;
 
+        public override IReadOnlyList<Type> RequiredTypes => new[]
+        {
+            typeof(Menu),
+            typeof(BasicMenu),
+            typeof(ContextMenuContainer),
+            typeof(BasicContextMenuContainer)
+        };
+
         private ContextMenuBox makeBox(Anchor anchor) =>
             new ContextMenuBox
             {
···
 
         public TestCaseContextMenu()
         {
-            Add(new ContextMenuContainer
+            Add(new BasicContextMenuContainer
             {
                 RelativeSizeAxes = Axes.Both,
                 Children = new[]

osu.Framework.Tests/Visual/UserInterface/TestCaseNestedMenus.cs

···
         private const int max_depth = 5;
         private const int max_count = 5;
 
-        public override IReadOnlyList<Type> RequiredTypes => new[] { typeof(Menu) };
+        public override IReadOnlyList<Type> RequiredTypes => new[]
+        {
+            typeof(Menu),
+            typeof(BasicMenu)
+        };
 
         private Random rng;
 
···
             }
         };
 
-        private class ClickOpenMenu : Menu
+        private class ClickOpenMenu : BasicMenu
         {
             protected override Menu CreateSubMenu() => new ClickOpenMenu(HoverOpenDelay, false);
 

osu.Framework/Graphics/Cursor/BasicContextMenuContainer.cs

···
+// Copyright (c) ppy Pty Ltd <[e-mail]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Graphics.UserInterface;
+
+namespace osu.Framework.Graphics.Cursor
+{
+    public class BasicContextMenuContainer : ContextMenuContainer
+    {
+        protected override Menu CreateMenu() => new BasicMenu(Direction.Vertical);
+    }
+}

osu.Framework/Graphics/UserInterface/BasicMenu.cs

···
+// Copyright (c) ppy Pty Ltd <[e-mail]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Graphics.Sprites;
+
+namespace osu.Framework.Graphics.UserInterface
+{
+    public class BasicMenu : Menu
+    {
+        public BasicMenu(Direction direction, bool topLevelMenu = false)
+            : base(direction, topLevelMenu)
+        {
+            BackgroundColour = FrameworkColour.Blue;
+        }
+
+        protected override Menu CreateSubMenu() => new BasicMenu(Direction.Vertical)
+        {
+            Anchor = Direction == Direction.Horizontal ? Anchor.BottomLeft : Anchor.TopRight
+        };
+
+        protected override DrawableMenuItem CreateDrawableMenuItem(MenuItem item) => new BasicDrawableMenuItem(item);
+
+        public class BasicDrawableMenuItem : DrawableMenuItem
+        {
+            public BasicDrawableMenuItem(MenuItem item)
+                : base(item)
+            {
+                BackgroundColour = FrameworkColour.BlueGreen;
+                BackgroundColourHover = FrameworkColour.Green;
+            }
+
+            protected override Drawable CreateContent() => new SpriteText
+            {
+                Anchor = Anchor.CentreLeft,
+                Origin = Anchor.CentreLeft,
+                Padding = new MarginPadding(2),
+                Font = new FontUsage("RobotoCondensed", weight: "Regular"),
+            };
+        }
+    }
+}