how can i insert , update or delete? i tried after choosing the data source , it shows the data correctly but when i edit or add a new item the database is not affected (allow edit,delete and add row are set to true)

Hello,

Please create a GridViewDateTimeOffsetColumn to support DateTimeOffset type.
A datetimeoffset editor would be good and support of nullable date types.

Thank you!

How to reproduce: check the attached project and comment the workaround

Workaround: 
public partial class RadForm1 : Telerik.WinControls.UI.RadForm
{
    private BindingList<TestDataObject> data;
    public RadForm1()
    {
        InitializeComponent();

        this.data = new BindingList<TestDataObject>();
        this.LoadData();

        GridViewTextBoxColumn textColumn = new GridViewTextBoxColumn();
        textColumn.Name = "Name";
        textColumn.FieldName = "Name";
        textColumn.HeaderText = "Name";
        this.radGridView1.Columns.Add(textColumn);

        GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn();
        dateColumn.Name = "Date";
        dateColumn.FieldName = "Date";
        dateColumn.HeaderText = "Date";
        this.radGridView1.Columns.Add(dateColumn);

        GridViewMaskBoxColumn maskBoxColumn = new GridViewMaskBoxColumn();
        maskBoxColumn.Name = "Price";
        maskBoxColumn.FieldName = "Price";
        maskBoxColumn.HeaderText = "Price";
        maskBoxColumn.MaskType = MaskType.Numeric;
        maskBoxColumn.Mask = "C";
        maskBoxColumn.TextAlignment = ContentAlignment.BottomRight;
        maskBoxColumn.FormatString = "{0:C}";
        maskBoxColumn.DataType = typeof(decimal);
        this.radGridView1.Columns.Add(maskBoxColumn);

        this.radGridView1.DataSource = this.data;
        this.radGridView1.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill;

        //Workaround
        this.radGridView1.CellBeginEdit += RadGridView1_CellBeginEdit;
        this.radGridView1.EditorRequired += RadGridView1_EditorRequired;
    }

    void RadGridView1_EditorRequired(object sender, EditorRequiredEventArgs e)
    {
        if (e.EditorType == typeof(RadMaskedEditBoxEditor))
        {
            e.EditorType = typeof(MyRadMaskedEditBoxEditor);
        }
    }

    private void RadGridView1_CellBeginEdit(object sender, GridViewCellCancelEventArgs e)
    {
        RadMaskedEditBoxEditor maskedEditBoxEditor = e.ActiveEditor as RadMaskedEditBoxEditor;
        if (maskedEditBoxEditor != null && e.Row.Cells[e.ColumnIndex].Value == null)
        {
            maskedEditBoxEditor.MaskTextBox.EnableNullValueInput = true;
        }
        else
        {
            maskedEditBoxEditor.MaskTextBox.EnableNullValueInput = false;
        }
    }

    private void LoadData()
    {
        for (int i = 0; i < 1000; i++)
        {
            decimal? price = null;
            if (i % 2 == 0)
            {
                price = i * 100;
            }

            this.data.Add(new TestDataObject
            {
                Name = "Name " + i,
                Date = DateTime.Now.AddDays(i),
                Price = price
            });
        }
    }
}

public class TestDataObject
{
    public string Name { get; set; }

    public DateTime Date { get; set; }

    public decimal? Price { get; set; }
}

public class MyRadMaskedEditBoxEditor : RadMaskedEditBoxEditor
{
    public override object Value
    {
        get
        {
            return base.Value;
        }
        set
        {
            if (value == null && (this.MaskTextBox.EnableNullValueInput || this.MaskTextBox.MaskType != MaskType.Numeric))
            {
                this.MaskTextBox.Value = this.NullValue;
            }
            else
            {
                base.Value = value;
            }
        }
    }
}

To reproduce: please refer to the attached sample project and gif file.

Workaround: add the column programmatically, not at design time.

To reproduce:
private void RadGridView1_UserAddingRow(object sender, Telerik.WinControls.UI.GridViewRowCancelEventArgs e)
{
    radGridView1.MasterView.TableAddNewRow.CancelAddNewRow();
}
See attached video.

Workaround:
private void RadGridView1_UserAddingRow(object sender, Telerik.WinControls.UI.GridViewRowCancelEventArgs e)
{
    radGridView1.MasterView.TableAddNewRow.CancelAddNewRow();
    radGridView1.MasterView.ViewTemplate.DataView.CurrentItem.IsCurrent = false;
}

Use attached to reproduce.

Workaround
- Set the position at runtime. 
   Me.radGridView1.MasterTemplate.AddNewRowPosition = Telerik.WinControls.UI.SystemRowPosition.Bottom

Use attached to reproduce.

With versions prior 2015.3.930 the results are different.

I have a GridView (Winforms v. 2017.3.1017.40, same problem with 2017.2.502.40) configured as on the attached screenshot (made some groups, made a search, and used the "excel-like" filter on a column to uncheck some values).

Then I try to click on some column headers to sort the grid.
After a few clicks, I get this error :
InvalidOperationException: La collection a été modifiée ; l'opération d'énumération peut ne pas s'exécuter.

I got different stacktrace with the same error :
InvalidOperationException: La collection a été modifiée ; l'opération d'énumération peut ne pas s'exécuter.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
   at Telerik.WinControls.UI.GridViewGroupRowInfo.get_ChildRows()
   at Telerik.WinControls.UI.GridViewRowInfo.HasChildRows()
   at Telerik.WinControls.UI.PrintGridTraverser.CanStepInHierarchy()
   at Telerik.WinControls.UI.GridTraverser.StepInHierarchy()
   at Telerik.WinControls.UI.GridTraverser.MoveNextCore()
   at Telerik.WinControls.UI.GridTraverser.MoveNext()
   at Telerik.WinControls.UI.GridViewSearchRowInfo.worker_DoWork(Object sender, DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)

-----

InvalidOperationException: Failed to compare two elements in the array. ---> NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.GridViewRowInfoComparer.CompareRows(GridViewRowInfo x, GridViewRowInfo y, SortDescriptorCollection context)
   at System.Collections.Generic.ArraySortHelper`1.InternalBinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)
   at System.Collections.Generic.ArraySortHelper`1.BinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)


   --- End of inner exception stack trace ---
   at System.Collections.Generic.ArraySortHelper`1.BinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)
   at System.Collections.Generic.List`1.BinarySearch(Int32 index, Int32 count, T item, IComparer`1 comparer)
   at Telerik.Collections.Generic.HybridIndex`1.PerformWithQuickSort()
   at Telerik.Collections.Generic.HybridIndex`1.get_Items()
   at Telerik.Collections.Generic.Index`1.GetEnumerator()
   at Telerik.WinControls.Data.GroupBuilder`1.Perform(IReadOnlyCollection`1 items, Int32 level, Group`1 parent)
   at Telerik.WinControls.Data.GroupBuilder`1.get_Groups()
   at Telerik.WinControls.UI.GridViewInfo.Refresh()
   at Telerik.WinControls.UI.GridViewInfo.get_ChildRows()
   at Telerik.WinControls.UI.ViewInfoTraverser.SetCollectionForStage(Boolean initializeCollection)
   at Telerik.WinControls.UI.ViewInfoTraverser.ChangeCollectionForward()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNextCore()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNext()
   at Telerik.WinControls.UI.GridTraverser.MoveNextCore()
   at Telerik.WinControls.UI.GridTraverser.MoveNext()
   at Telerik.WinControls.UI.BaseGridNavigator.NavigateToRow(GridViewRowInfo row, Boolean select)
   at Telerik.WinControls.UI.BaseGridNavigator.ProcessViewChangedEvent(GridViewEvent eventData)
   at Telerik.WinControls.UI.BaseGridNavigator.ProcessEventCore(GridViewEvent eventData)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessCollection(GridViewEvent gridEvent, PriorityWeakReferenceList list, GridEventProcessMode processMode)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.NotifyListeners(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.FlushEvents()
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewTemplate template, GridViewEvent eventData, Boolean postUI)
   at Telerik.WinControls.UI.GridViewTemplate.DispatchDataViewChangedEvent(Object sender, DataViewChangedEventArgs args)
   at Telerik.WinControls.UI.GridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.UI.MasterGridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.Data.RadDataView`1.RebuildData(Boolean notify)
   at Telerik.WinControls.Data.RadDataView`1.OnNotifyPropertyChanged(PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.RadCollectionView`1.OnNotifyPropertyChanged(String propertyName)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.SortDescriptor.set_Direction(ListSortDirection value)
   at Telerik.WinControls.UI.GridViewColumn.Sort(RadSortOrder sortOrder, Boolean multiSortMode)
   at Telerik.WinControls.UI.GridHeaderCellElement.Sort(RadSortOrder sortOrder)
   at Telerik.WinControls.UI.GridHeaderRowBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.BaseGridBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadGridView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

------

InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
[...]
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Alto.Client.Controls.Dispatch.DispatchResources.DeliveryPointFilterManager.get_DeliveryPointsVisible() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\DeliveryPointFilterManager.cs:line 38
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.get_Title() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 1520
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.updatePanelTitle() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 543
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.onFilterChanged(Object sender, GridViewCollectionChangedEventArgs e) in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 547
   at Telerik.WinControls.UI.GridViewCollectionChangedEventHandler.Invoke(Object sender, GridViewCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnFilterChanged(Object sender, GridViewCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.EventDispatcher.RaiseEvent[T](Object eventKey, Object sender, T args)
   at Telerik.WinControls.UI.GridViewFilterDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at Telerik.Collections.Generic.NotifyCollection`1.InsertItem(Int32 index, T item)
   at Telerik.WinControls.UI.GridViewFilterDescriptorCollection.InsertItem(Int32 index, FilterDescriptor item)
   at System.Collections.ObjectModel.Collection`1.Add(T item)
   at Telerik.WinControls.UI.GridViewDataColumn.SetFilterDescriptor(FilterDescriptor value)
   at Telerik.WinControls.UI.GridHeaderCellElement.filterPopup_FilterConfirmed(Object sender, EventArgs e)
   at Telerik.WinControls.UI.BaseFilterPopup.OnFilterConfirmed()
   at Telerik.WinControls.UI.RadListFilterPopup.OnButtonOkClick(EventArgs e)
   at Telerik.WinControls.UI.RadListFilterPopup.ButtonOK_Click(Object sender, EventArgs e)
   at Telerik.WinControls.RadElement.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonItem.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonElement.OnClick(EventArgs e)
   at Telerik.WinControls.RadElement.DoClick(EventArgs e)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.DoMouseUp(MouseEventArgs e)
   at Telerik.WinControls.ComponentInputBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.RadControl.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadPopupControlBase.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

----

InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
   at Telerik.WinControls.Data.GroupBuilder`1.Perform(IReadOnlyCollection`1 items, Int32 level, Group`1 parent)
   at Telerik.WinControls.Data.DataItemGroup`1.get_Groups()
   at Telerik.WinControls.UI.DataGroup.get_Groups()
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateSummaryRowsCore(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateSummaryRowsCore(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateGroupSummaryRows(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.RefreshSummaryRowsInGroup(NotifyCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.GridViewTemplate.RefreshAggregates(NotifyCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.MasterGridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.Data.RadDataView`1.RebuildData(Boolean notify)
   at Telerik.WinControls.Data.RadDataView`1.OnNotifyPropertyChanged(PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.RadCollectionView`1.OnNotifyPropertyChanged(String propertyName)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.RemoveItem(Int32 index)
   at Telerik.WinControls.UI.GridViewColumn.Sort(RadSortOrder sortOrder, Boolean multiSortMode)
   at Telerik.WinControls.UI.GridHeaderCellElement.Sort(RadSortOrder sortOrder)
   at Telerik.WinControls.UI.GridHeaderRowBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.BaseGridBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadGridView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

To reproduce:
- Create a self reference grid and set the columns width so the horizontal scrollbar is visible. 
- Scroll to the right and filter by the last column,
- Type a single character, the the edited cell is now changed. 

Workaround:
class MyFilterCell : GridFilterCellElement
{
    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(GridFilterCellElement);
        }
    }

    public MyFilterCell(GridViewDataColumn column, GridRowElement row) : base(column, row)
    {
        
    }
    public override bool IsCompatible(GridViewColumn data, object context)
    {
        return false;
    }
}

Use attached to reproduce.


Workaround: 

this.LoadFieldList(hiddenGrid.MasterTemplate);
this.FieldList.Add(new Telerik.Data.Expressions.ExpressionItem()
{ Name = "Test", Description = "Test", Syntax = "Test", Type = Telerik.Data.Expressions.ExpressionItemType.Field, Value = "Test" });

Use attached to reproduce.
- Use a 125% and 150% monitor for reproducing.
- This should be tested on Windows 10 1803 (Spring Update) as well.

Workaround:
private void RadGridView1_ColumnChooserCreated(object sender, Telerik.WinControls.UI.ColumnChooserCreatedEventArgs e)
{
    e.ColumnChooser = new MyColumnChooser(this.radGridView1.MasterTemplate, radGridView1.GridViewElement);
}

public partial class MyColumnChooser : GridViewColumnChooser
{
    public MyColumnChooser()
    {
        InitializeComponent();
    }
    public MyColumnChooser(GridViewTemplate template, RadGridViewElement rootElement) : base(template, rootElement)
    {
    }
    SizeF oldDpi = new SizeF(1, 1);
    protected override void HandleDpiChanged()
    {

        base.HandleDpiChanged();
        SizeF descale = new SizeF(1f / this.FormElement.DpiScaleFactor.Width, 1f / this.FormElement.DpiScaleFactor.Height);
        this.Scale(descale);
        var dpi = NativeMethods.GetMonitorDpi(Screen.FromRectangle(this.Bounds), NativeMethods.DpiType.Effective);
        if (oldDpi != dpi)
        {
            SizeF sz = new SizeF(dpi.Width / oldDpi.Width, dpi.Height / oldDpi.Height);
       
            this.Scale(dpi);
        }

        oldDpi = dpi;
    }
   
}

Please refer to the attached sample project and follow the steps illustrated in the gif file.

Note: the same behavior is observed with the CellValidating event in the new row.

Workaround: use the RowValidating event instead:

        private void radGridView1_RowValidating(object sender, Telerik.WinControls.UI.RowValidatingEventArgs e)
        {
            if (e.Row is Telerik.WinControls.UI.GridViewNewRowInfo && e.Row.Cells["Id"].Value == null)
            {
                this.radGridView1.MasterView.TableAddNewRow.CancelAddNewRow();
                this.radGridView1.CurrentRow = this.radGridView1.MasterView.TableAddNewRow;
            }
        }
 
NOTE: The CellValidating event is fired multiple times as well when you select a new tab in RadDock. There is a second project attached.

A similar issue can be also observed in RadTreeView:

Workaround RadGridView: 
private void RadGridView1_CellEditorInitialized(object sender, GridViewCellEventArgs e)
{
    RadTextBoxEditor editor = e.ActiveEditor as RadTextBoxEditor;
    if (editor != null)
    {
        editor.EditorElement.MinSize = new Size(0, 30);
    }
}

Workaround RadTreeView:
 
private void RadTreeView1_EditorInitialized(object sender, TreeNodeEditorInitializedEventArgs e)
{
    TreeViewTextBoxEditor editor = e.Editor as TreeViewTextBoxEditor;
    if (editor != null)
    {
        ((BaseTextBoxEditorElement)editor.EditorElement).TextBoxItem.TextBoxControl.MinimumSize = new Size(0, 24);
    }
}

In 125% the RadTextBox in the Fluent theme keeps shrinking:

Workaround
public RadForm1()
{
    InitializeComponent();

    SizeF dpi = NativeMethods.GetMonitorDpi(Screen.PrimaryScreen, NativeMethods.DpiType.Effective);
    this.radTextBox1.MinimumSize = new Size(0, (int)(24 * dpi.Height));
}

Use attached to reproduce.

Workaround:
private void RadGridView1_ColumnChooserCreated(object sender, Telerik.WinControls.UI.ColumnChooserCreatedEventArgs e)
{
    var columnChooser = e.ColumnChooser as GridViewColumnChooser;
    columnChooser.Shown -= ColumnChooser_Shown;
    columnChooser.Shown += ColumnChooser_Shown;
  
}

private void ColumnChooser_Shown(object sender, EventArgs e)
{
    var columnChooser = sender as GridViewColumnChooser;
    var factor = this.FormElement.DpiScaleFactor;
    columnChooser.Scale(factor);
}

Use attached to reproduce.

Workaround:

Use CellFormatting instead of RowFormating. 

To reproduce:
private void radButton1_Click(object sender, EventArgs e)
{
    radGridView1.MasterView.TableSearchRow.SelectNextSearchResult();

}
Check the index in the search textbox, it is not updated. 

Workaround:
var cell = radGridView1.TableElement.FindDescendant<GridSearchCellElement>();
if (cell != null)
{
    cell.FindNextButton.PerformClick();
}

To reproduce:
Use the following code
private void RadGridView1_UserAddingRow(object sender, GridViewRowCancelEventArgs e)
{
    radGridView1.MasterView.TableAddNewRow.CancelAddNewRow();
    radGridView1.MasterView.ViewTemplate.DataView.CurrentItem.IsCurrent = false;
}

Place the new row at the bottom. While in edit mode press tab to fill until an exception is thrown.

Workaround:
BaseGridBehavior gridBehavior = radGridView1.GridBehavior as BaseGridBehavior;
gridBehavior.UnregisterBehavior(typeof(GridViewNewRowInfo));
gridBehavior.RegisterBehavior(typeof(GridViewNewRowInfo), new CustomGridRowBehavior());


internal class CustomGridRowBehavior : GridNewRowBehavior
{
    protected override bool ProcessTabKey(KeyEventArgs keys)
    {
        bool newRowIsInEditMode = this.IsInEditMode && this.GridViewElement.CurrentRow is GridViewNewRowInfo;

        if ( newRowIsInEditMode  && this.GridViewElement.Navigator.IsLastEditableColumn(this.GridViewElement.CurrentColumn))              
        {
            this.GridViewElement.Navigator.SelectFirstColumn();

            while (this.GridViewElement.CurrentColumn.ReadOnly && this.GridViewElement.Navigator.SelectNextColumn())
            { }
            return false;
        }
        return base.ProcessTabKey(keys);
    }
}

Use attached to reproduce.

Workaround:

DragDropService.AllowAutoScrollColumnsWhileDragging = false;
DragDropService.AllowAutoScrollRowsWhileDragging = false;