handle OS window size changes

src/Game.cs

@@ -213,10 +213,22 @@ namespace MoonWorks
 					case SDL.SDL_EventType.SDL_CONTROLLERDEVICEREMOVED:
 						HandleControllerRemoved(_event);
 						break;
+
+					case SDL.SDL_EventType.SDL_WINDOWEVENT:
+						HandleWindowEvent(_event);
+						break;
 				}
 			}
 		}
 
+		private void HandleWindowEvent(SDL.SDL_Event evt)
+		{
+			if (evt.window.windowEvent == SDL.SDL_WindowEventID.SDL_WINDOWEVENT_SIZE_CHANGED)
+			{
+				Window.SizeChanged((uint) evt.window.data1, (uint) evt.window.data2);
+			}
+		}
+
 		private void HandleTextInput(SDL.SDL_Event evt)
 		{
 			// Based on the SDL2# LPUtf8StrMarshaler

src/Window.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using SDL2;
 
 namespace MoonWorks
@@ -81,6 +81,12 @@ namespace MoonWorks
 			Height = height;
 		}
 
+		internal void SizeChanged(uint width, uint height)
+		{
+			Width = width;
+			Height = height;
+		}
+
 		protected virtual void Dispose(bool disposing)
 		{
 			if (!IsDisposed)