WPF DataGrid左上角选择所有标题按钮不对焦网格

Question

My control uses a WPF DataGrid. If you click the empty header in the top left it selects all rows. This is a standard part of DataGrid, not anything I've added.

However, my users are having trouble because this 'button' doesn't focus the DataGrid. How can I fix this?

System.Windows.Controls.DataGrid

Edit: This is the Excel analogue of the DataGrid button I am talking about. It's not a true button, but a header of some kind:

Answer 1

If you look in Snoop you can notice this button.

So you can write event handler to Click event for this button and in this handler you can focus the grid.

private void myGrid_Loaded(object sender, RoutedEventArgs e)
{
    DataGrid dg = sender as DataGrid;
    Border border = VisualTreeHelper.GetChild(dg, 0) as Border;
    ScrollViewer scrollViewer = VisualTreeHelper.GetChild(border, 0) as ScrollViewer;
    Grid grid = VisualTreeHelper.GetChild(scrollViewer, 0) as Grid;
    Button button = VisualTreeHelper.GetChild(grid, 0) as Button;

    if (button != null && button.Command != null && button.Command == DataGrid.SelectAllCommand)
    {
        button.Click += new RoutedEventHandler(button_Click);
    }         
}

void button_Click(object sender, RoutedEventArgs e)
{     
    myGrid.Focus();           
}

Answer 2

I used an alternative that doesn't rely on the the visual tree for the control:

In the XAML:

<DataGrid.CommandBindings>
<CommandBinding Command="SelectAll" Executed="MyGrid_SelectAll"/></DataGrid.CommandBindings>

In the code:

private void MyGrid_SelectAll(object sender, ExecutedRoutedEventArgs e)
    {
        var myGrid = (DataGrid)sender;
        myGrid.Focus();
        if (myGrid.SelectedCells.Count == myGrid.Columns.Count * myGrid.Items.Count)
        {
            myGrid.SelectedCells.Clear();
        }
        else
        {
            myGrid.SelectAll();
        }

        e.Handled = true;
    }

This also gave me the ability to implement deselect all if all cells are selected.