ToolKit DataGrid deselect all on LostFocus

datagrid, toolkit, wpf

Solution

According to my researches, attached behavior is the only acceptable solution for me. Hope this will help somebody more:

public class DataGridBehavior
{
    public static readonly DependencyProperty IsDeselectOnLostFocusProperty =
    DependencyProperty.RegisterAttached("IsDeselectOnLostFocus", typeof(bool), typeof(DataGridBehavior), new UIPropertyMetadata(false, PropertyChangedCallback));

    private static void PropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var dg = dependencyObject as DataGrid;
        if (dg == null)
            return;

        if (e.NewValue is bool == false)
            return;

        if ((bool)e.NewValue)
            dg.LostFocus += dg_LostFocus;
    }

    static void dg_LostFocus(object sender, RoutedEventArgs e)
    {
        (sender as DataGrid).SelectedIndex = -1;
    }

    public static bool GetIsDeselectOnLostFocus(DataGrid dg)
    {
        return(bool)dg.GetValue(IsDeselectOnLostFocusProperty);
    }

    public static void SetIsDeselectOnLostFocus(DataGrid dg, bool value)
    {
        dg.SetValue(IsDeselectOnLostFocusProperty, value);
    }
}

Then:

<Style TargetType="{x:Type DataGrid}">
    <Setter Property="helpers:DataGridBehavior.IsDeselectOnLostFocus" Value="True"/>
</Style>

Problem

I'm trying to create a style which will make all my DataGrids select row -1 when they lose focus. I'm doing: ``` <Style TargetType="{x:Type DataGrid}"> <Style.Triggers> <EventTrigger RoutedEvent="DataGrid.LostFocus"> <BeginStoryboard> <Storyboard> <Int32AnimationUsingKeyFrames Storyboard.TargetProperty="(DataGrid.SelectedIndex)"> <DiscreteInt32KeyFrame KeyTime="00:00:00" Value="-1" /> </Int32AnimationUsingKeyFrames> </Storyboard> </BeginStoryboard> </EventTrigger> </Style.Triggers> </Style> ``` It works only for the first time the focus is lost, but on the second time program crashes because of type conversion ecxeption. Is it possible without code behind?

Original source