Implemented Layers and LayerStack

Sandbox/src/SandboxApp.bf

@@ -1,17 +1,44 @@
 using System;
 using GlitchyEngine;
+using GlitchyEngine.Events;
 using System.Diagnostics;
 using GlitchLog;
 
 namespace Sandbox
 {
+	class ExampleLayer : Layer
+	{
+		[AllowAppend]
+		public this() : base("Example") {  }
+
+		public override void Update()
+		{
+			Log.ClientLogger.Info("ExampleLayer.Update");
+
+			// Just for temporary vsyncing
+			// Todo: remove
+			DwmFlush();
+		}
+
+		[CLink, Import("Dwmapi.lib")]
+		static extern void DwmFlush();
+
+		public override void OnEvent(Event event)
+		{
+			Log.ClientLogger.Trace("{}", event);
+		}
+	}
+
 	class SandboxApp : Application
 	{
+		public this()
+		{
+			PushLayer(new ExampleLayer());
+		}
+
 		[Export, LinkName("CreateApplication")]
 		public static Application CreateApplication()
 		{
-
-
 			return new SandboxApp();
 		}
 	}