Fix DataGrid scrolling

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -178,9 +178,9 @@ namespace Avalonia.Controls
                 {
                     var handled = OwningGrid.UpdateStateOnMouseLeftButtonDown(e, ColumnIndex, OwningRow.Slot, !e.Handled);
 
-                    // Do not handle PointerPressed with touch,
+                    // Do not handle PointerPressed with touch or pen,
                     // so we can start scroll gesture on the same event.
-                    if (e.Pointer.Type != PointerType.Touch)
+                    if (e.Pointer.Type != PointerType.Touch && e.Pointer.Type != PointerType.Pen)
                     {
                         e.Handled = handled;
                     }