Allow horizontal scrolling if the horizontal scrollbar is not disable…

…d and the vertical scrollbar is disabled (#3174)

* Fixes #3170 - A horizontal scroll happens if the mouse has a horizontal wheel OR if the horizontal scrollbar is not disabled AND the vertical scrollbar IS disabled

* Only scroll opposite if the scroll happened from a horizontal scroll

* Correct or statement

Co-authored-by: Michael Hawker MSFT (XAML Llama) <michael.hawker@outlook.com>

Microsoft.Toolkit.Uwp.UI.Controls.DataGrid/DataGrid/DataGrid.cs

@@ -3712,7 +3712,10 @@ protected override void OnPointerWheelChanged(PointerRoutedEventArgs e)
             if (!e.Handled)
             {
                 PointerPoint pointerPoint = e.GetCurrentPoint(this);
-                bool isForHorizontalScroll = pointerPoint.Properties.IsHorizontalMouseWheel;
+
+                // A horizontal scroll happens if the mouse has a horizontal wheel OR if the horizontal scrollbar is not disabled AND the vertical scrollbar IS disabled
+                bool isForHorizontalScroll = pointerPoint.Properties.IsHorizontalMouseWheel ||
+                    (this.HorizontalScrollBarVisibility != ScrollBarVisibility.Disabled && this.VerticalScrollBarVisibility == ScrollBarVisibility.Disabled);
 
                 if ((isForHorizontalScroll && this.HorizontalScrollBarVisibility == ScrollBarVisibility.Disabled) ||
                     (!isForHorizontalScroll && this.VerticalScrollBarVisibility == ScrollBarVisibility.Disabled))
@@ -3721,7 +3724,7 @@ protected override void OnPointerWheelChanged(PointerRoutedEventArgs e)
                 }
 
                 double offsetDelta = -pointerPoint.Properties.MouseWheelDelta / DATAGRID_mouseWheelDeltaDivider;
-                if (isForHorizontalScroll)
+                if (isForHorizontalScroll && pointerPoint.Properties.IsHorizontalMouseWheel)
                 {
                     offsetDelta *= -1.0;
                 }