Add some missing Dispose calls, fix some Dispose implementations.

OpenRA.Mods.Common/LoadScreens/BlankLoadScreen.cs

@@ -90,6 +90,12 @@ namespace OpenRA.Mods.Common.LoadScreens
 			Game.Settings.Save();
 		}
 
-		public virtual void Dispose() { }
+		protected virtual void Dispose(bool disposing) { }
+
+		public void Dispose()
+		{
+			Dispose(true);
+			GC.SuppressFinalize(this);
+		}
 	}
 }

OpenRA.Mods.Common/LoadScreens/LogoStripeLoadScreen.cs

@@ -79,12 +79,12 @@ namespace OpenRA.Mods.Common.LoadScreens
 			r.EndFrame(new NullInputHandler());
 		}
 
-		public override void Dispose()
+		protected override void Dispose(bool disposing)
 		{
-			if (sheet != null)
+			if (disposing && sheet != null)
 				sheet.Dispose();
 
-			base.Dispose();
+			base.Dispose(disposing);
 		}
 	}
 }

OpenRA.Mods.Common/Widgets/RadarWidget.cs

@@ -19,7 +19,7 @@ using OpenRA.Widgets;
 
 namespace OpenRA.Mods.Common.Widgets
 {
-	public class RadarWidget : Widget
+	public sealed class RadarWidget : Widget, IDisposable
 	{
 		public string WorldInteractionController = null;
 		public int AnimationLength = 5;
@@ -447,6 +447,12 @@ namespace OpenRA.Mods.Common.Widgets
 			base.Removed();
 			world.Map.MapTiles.Value.CellEntryChanged -= UpdateTerrainCell;
 			world.Map.CustomTerrain.CellEntryChanged -= UpdateTerrainCell;
+			Dispose();
+		}
+
+		public void Dispose()
+		{
+			radarSheet.Dispose();
 		}
 	}
 }