The engine now uses the SDL2.0 scroll events properly.

Scroll speed is now a user preference.

OpenRA.Game/IInputHandler.cs

@@ -20,19 +20,21 @@ namespace OpenRA
 		void OnTextInput(string text);
 	}
 
-	public enum MouseInputEvent { Down, Move, Up }
+	public enum MouseInputEvent { Down, Move, Up, Scroll }
 	public struct MouseInput
 	{
 		public MouseInputEvent Event;
 		public MouseButton Button;
+		public int ScrollDelta;
 		public int2 Location;
 		public Modifiers Modifiers;
 		public int MultiTapCount;
 
-		public MouseInput(MouseInputEvent ev, MouseButton button, int2 location, Modifiers mods, int multiTapCount)
+		public MouseInput(MouseInputEvent ev, MouseButton button, int scrollDelta, int2 location, Modifiers mods, int multiTapCount)
 		{
 			Event = ev;
 			Button = button;
+			ScrollDelta = scrollDelta;
 			Location = location;
 			Modifiers = mods;
 			MultiTapCount = multiTapCount;
@@ -45,9 +47,7 @@ namespace OpenRA
 		None = 0,
 		Left = 1,
 		Right = 2,
-		Middle = 4,
-		WheelDown = 8,
-		WheelUp = 16
+		Middle = 4
 	}
 
 	[Flags]

OpenRA.Game/Settings.cs

@@ -131,6 +131,7 @@ namespace OpenRA
 		public bool ViewportEdgeScroll = true;
 		public MouseScrollType MouseScroll = MouseScrollType.Standard;
 		public float ViewportEdgeScrollStep = 10f;
+		public float UIScrollSpeed = 50f;
 
 		public bool UseClassicMouseStyle = false;
 		public bool AlwaysShowStatusBars = false;

OpenRA.Game/Widgets/ScrollPanelWidget.cs

@@ -23,7 +23,6 @@ namespace OpenRA.Widgets
 	public class ScrollPanelWidget : Widget
 	{
 		public int ScrollbarWidth = 24;
-		public float ScrollVelocity = 4f;
 		public int ItemSpacing = 2;
 		public int ButtonDepth = ChromeMetrics.Get<int>("ButtonDepth");
 		public string Background = "scrollpanel-bg";
@@ -130,9 +129,9 @@ namespace OpenRA.Widgets
 			return EventBounds;
 		}
 
-		void Scroll(int direction)
+		void Scroll(int amount)
 		{
-			ListOffset += direction*ScrollVelocity;
+			ListOffset += amount * Game.Settings.Game.UIScrollSpeed;
 			ListOffset = Math.Min(0,Math.Max(Bounds.Height - ContentHeight, ListOffset));
 		}
 
@@ -188,15 +187,9 @@ namespace OpenRA.Widgets
 		int2 lastMouseLocation;
 		public override bool HandleMouseInput(MouseInput mi)
 		{
-			if (mi.Button == MouseButton.WheelDown)
+			if (mi.Event == MouseInputEvent.Scroll)
 			{
-				Scroll(-1);
-				return true;
-			}
-
-			if (mi.Button == MouseButton.WheelUp)
-			{
-				Scroll(1);
+				Scroll(mi.ScrollDelta);
 				return true;
 			}