Thanks for the quick reply.We don't want to use the DateColumn, because by default they get rendered as DatePicker and users don't want it. 

Our grid's dynamic and have couple of  other custom columns which are working fine...

Here's the 3 classes as such and u can easily reproduce the issue

public class CustomDateColumn : EditableColumn   

    {

        protected override ColumnContentProviderBase GenerateContentProvider()

        {

            return new CustomDateColumnProvider();

        }

    }

  public class CustomDateColumnProvider : ColumnContentProviderBase

    {

        XamMaskedEditor dp;

        TextBlock tb;

    public CustomDateColumnProvider()   

    {

        dp = new XamMaskedEditor();// DatePickerMaskedSingleControl();

        dp.Mask = "##/##/##";

        dp.PadChar = '_';

       // dp.ValueChanged += new RoutedEventHandler(dp_ValueChanged);

        dp.DataMode = MaskMode.IncludeLiteralsWithPadding;

        dp.DisplayMode = MaskMode.IncludeLiteralsWithPadding;

        dp.ValidationMode = ValidationMode.LostFocus;

        tb = new TextBlock();

        dp.LostFocus += new RoutedEventHandler(dp_LostFocus);

    }

    void dp_LostFocus(object sender, RoutedEventArgs e)

    {

    }

    public override FrameworkElement ResolveDisplayElement(Cell cell,    

         System.Windows.Data.Binding cellBinding)   

    {

        CustomDateColumn  column = (CustomDateColumn)cell.Column;

        Binding textBinding = new Binding();

        textBinding.Path = new PropertyPath(column.Key);

        textBinding.Converter = new DateConverter();

        textBinding.Mode = BindingMode.TwoWay;

        this.tb.SetBinding(TextBlock.TextProperty, textBinding);

        return tb; 

    }

    protected override System.Windows.FrameworkElement ResolveEditorControl(Cell cell, object editorValue, double availableWidth, double availableHeight, Binding editorBinding)

    {

        CustomDateColumn column = (CustomDateColumn)cell.Column;

        Binding textBinding = new Binding();

        textBinding.Source = cell.Row.Data;

        textBinding.Path = new PropertyPath(column.Key);

        textBinding.Mode = BindingMode.TwoWay;

        textBinding.Converter = new DateConverter();

        this.dp.SetBinding(XamMaskedEditor.ValueProperty, textBinding);

        return this.dp;

    }

    public override object ResolveValueFromEditor(Cell cell)

    {

        return this.dp.Value;

    }

    }

    public class DateConverter : IValueConverter

    {

        public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            string retString = string.Empty;

            string formatString = "MM/dd/yy"; //Default date format

            //return string.Format(System.Convert.ToString(parameter), decimal.Parse(System.Convert.ToString(value)));

            if (parameter != null)  // default 

            {

                if (!string.IsNullOrWhiteSpace(parameter.ToString()))

                {

                    formatString = parameter.ToString().Trim();

                }

            }

            if (value != null && !string.IsNullOrWhiteSpace(value.ToString()))

            {

                // retString = System.String.Format(formatString, System.Convert.ChangeType(value, typeof(DateTime), null));

                DateTime dtOut;

                if (DateTime.TryParse(value.ToString(), out dtOut))

                {

                    retString = System.Convert.ToDateTime(value).ToString(formatString);

                }

                else

                {

                    retString = value.ToString();

                }

            }

            return retString;

        }

        public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            return value;

        }

      }

the lost focus issue is still not solved.when the XamMaskedEditor has an invalid date and if we try to handle the that in the lost focus its not working..

this is the lost focus event in the CustomDateColumnProvider.

e)

{

.Empty;

;

)

{

.DEFAULT_TXT.Trim()))

{

dateValue;

dateValue))

{

)sender).Focus();

((

;

I might not be clear on your requirements.  The sample I attached does not have the LostFocus event wired up, nor does it need to.  If you provide an invalid date, the focus is not lost, but it remains in the cell's editor, as expected.  Is there a reason why you need to use LostFocus?

u are right ..if u use the XamMaskededitor in the Always mode, then it will stay focus. There also we had found an issue..If the editors value is an invalid date and the user  tries to focus on a Dropdownbox some where on the screen and selects a value it still looses focus..Which is Ok..Problem is one of our drop down is  allowing the user to put the grid in a read only mode..

When there is a erros in the date editor and the user goes to this  drop down and puts the grid in read only mode(none of the cells in the grid is edtable)  and comes back to edit mode by selecting the edit option from the drop down..the grid never becomes editable...(the problem I believe is the date picker which was in the edit mode with its focus still on on it) ....We some how solved by using the value changed event   and keeping the focus on the cell...

Ideally we wanted to use the LostFocus mode of the control  and not the Always mode for 2 reason ..,

1. To only show the error message when the user looses focus as against showing the error message always  till the data is corrected

2. Also we wanted to keep the focus on the cell, if the data is bad

It sounds as if you have worked around the issue, but are unable to get the ideal behavior.  If you would like me to research this further, please review the attached sample, which is a slight modification of the previous one I provided to make it a little closer to the application you described. (i.e. I merely added a stand-alone dropdown and wired up the LostFocus event.)

If you can either modify this sample, or guide me on how to do so such that it models your current situation....or supply a new sample of your own, I will be sure to investigate further.

Thanks,

As discussed the snippet in the  XamMaskedEditor lost focus inside the CustomeDateColumnProvider class ;

.Empty;

;

)

{

.DEFAULT_TXT.Trim()))

{

dateValue;

dateValue))

{

)sender).Focus();

((

;