WPF DataGrid horizontal scrollbar not showing

I also very much dislike this behavior, since I use header filters. My "hack" is much easier than the above: simply place the data grid inside a new ScrollViewer with HorizontalScrollBarVisibility=Auto and VerticalScrollBarVisibility=Disabled (the DataGrid already handles that one fine). Like so:

<ScrollViewer HorizontalScrollBarVisibility="Auto"
              VerticalScrollBarVisibility="Disabled">
    <DataGrid>
        ...
    </DataGrid>
</ScrollViewer>

Sure, it's more controls on the page, but a lot easier than the hacky code above. So far I haven't found a way to make the data grid do this automatically.

The side effect of this solution may be the vertical scrollbar hidden until you scroll to the right.

this was actually a major issue to me since I am creating many columns and allow the user to filter by having filter controls in the header.

When the user scrolls to the right and places a filter in a column and NO rows are returned because of these criteria then the entire grid would move to the left (all columns to the default left position) and the horizontal scrollbar would disappear so the user can't scroll to the filter column to undo his/her action!!

Major pain!

The 'hack' I have just placed in the code is a way around it: (the _dv pointing at a DataView from a DataTable)

// construct an overall sql filter statement
string sqlFilter = _setttings.SGColumns.GetFilterSQL();

BindingListCollectionView view = CollectionViewSource.GetDefaultView(gridMain.ItemsSource) as BindingListCollectionView;

if (view != null)
    view.CustomFilter = sqlFilter;      // "XGROUP = 'E' AND GEOG = 'U'";

if (view != null && _dv.Count == 0)
{
    gridMain.ItemsSource = null;
    gridMain.Items.Add("hello");
    _RowHeightTemp = gridMain.RowHeight;
    gridMain.RowHeight = 0;
}
else
{
    if (gridMain.Items.Count == 1 && gridMain.Items[0].ToString() == "hello")
    {
        gridMain.Items.Clear();
        gridMain.ItemsSource = _dv;
        view = CollectionViewSource.GetDefaultView(gridMain.ItemsSource) as BindingListCollectionView;
        view.CustomFilter = sqlFilter;
        gridMain.RowHeight = _RowHeightTemp;
    }
}

This now ensures that the grid stays in its exact position when the no rows are displayed!

I think that when the Datagrid is empty, the ScrollViewer doesn't handle anything. Try to fill the columns by adding an ItemsSource, the scrolling should therefore appear :)