Change color of labels that correspond to disabled inputs

- Add a new widget type for input and extend it from other input widgets
- Add a new label type that can be linked to an input widget
- Change the label color when the input's disabled state changes

OpenRA.Game/Widgets/Widget.cs

@@ -606,6 +606,25 @@ namespace OpenRA.Widgets
 		}
 	}
 
+	public class InputWidget : Widget
+	{
+		public bool Disabled = false;
+		public Func<bool> IsDisabled = () => false;
+
+		public InputWidget()
+		{
+			IsDisabled = () => Disabled;
+		}
+
+		public InputWidget(InputWidget other)
+			: base(other)
+		{
+			IsDisabled = () => other.Disabled;
+		}
+
+		public override Widget Clone() { return new InputWidget(this); }
+	}
+
 	public class WidgetArgs : Dictionary<string, object>
 	{
 		public WidgetArgs() { }