improve the classic mouse behaivor

- don't require to deselect units to change selection
- fix issue with broken building placement on right-click orders
- don't select enemy units when left-click attacking
- build palette won't interfere with unit orders anymore

OpenRA.Game/Widgets/WorldInteractionControllerWidget.cs

@@ -57,7 +57,6 @@ namespace OpenRA.Widgets
 
 			var HasBox = (SelectionBox != null) ? true : false;
 			var MultiClick = (mi.MultiTapCount >= 2) ? true : false;
-			var NothingSelected = !world.Selection.Actors.Any();
 
 			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Down)
 			{
@@ -66,7 +65,8 @@ namespace OpenRA.Widgets
 				
 				dragStart = dragEnd = xy;
 
-				if (UseClassicMouseStyle)
+				//place buildings
+				if (!UseClassicMouseStyle || (UseClassicMouseStyle && !world.Selection.Actors.Any()) )
 					ApplyOrders(world, xy, mi);
 			}
 			
@@ -75,9 +75,18 @@ namespace OpenRA.Widgets
 
 			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Up)
 			{
-				if (world.OrderGenerator is UnitOrderGenerator)
+				if (UseClassicMouseStyle && Focused)
 				{
-					if ((UseClassicMouseStyle && NothingSelected) || (!UseClassicMouseStyle))
+					//order units around
+					if (!HasBox && world.Selection.Actors.Any() && !MultiClick)
+					{
+						ApplyOrders(world, xy, mi);
+						LoseFocus(mi);
+						return true;
+					}
+				}
+
+				if (world.OrderGenerator is UnitOrderGenerator)
 				{
 					if (MultiClick)
 					{
@@ -97,7 +106,6 @@ namespace OpenRA.Widgets
 						world.Selection.Combine(world, newSelection, mi.Modifiers.HasModifier(Modifiers.Shift), dragStart == xy);
 					}
 				}
-				}
 				
 				dragStart = dragEnd = xy;
 				LoseFocus(mi);
@@ -110,7 +118,8 @@ namespace OpenRA.Widgets
 			{
 				if (UseClassicMouseStyle)
 					world.Selection.Clear();
-				else if (!HasBox)	// don't issue orders while selecting
+
+				if (!HasBox)	// don't issue orders while selecting
 					ApplyOrders(world, xy, mi);
 			}