Private Sub RadButton2_Click(sender As Object, e As EventArgs) Handles RadButton2.Click
        Dim spreadExporter As GridViewSpreadExport = New GridViewSpreadExport(gvAssetSchedule)
        AddHandler spreadExporter.CellFormatting, AddressOf spreadExporter_CellFormatting
        Dim exportRenderer As New SpreadExportRenderer()
        spreadExporter.ExportVisualSettings = True
        Dim filename = "..\..\export" & DateTime.Now.ToLongTimeString().Replace(":", "_") & ".xlsx"
        spreadExporter.RunExport(filename, exportRenderer)
        Process.Start(filename)
    End Sub

    Private Sub spreadExporter_CellFormatting(sender As Object, e As Telerik.WinControls.Export.CellFormattingEventArgs)
        If e.GridCellInfo Is Nothing Then
            Dim selection As CellSelection = e.CellSelection
            Dim range As CellRange = selection.CellRanges(0)
            Dim val = selection.Worksheet.Cells(range.FromIndex.RowIndex, range.FromIndex.ColumnIndex).GetValue()
            Dim format As New CellValueFormat("@")
            selection.Worksheet.Cells(range.FromIndex.RowIndex, range.FromIndex.ColumnIndex).SetFormat(format)
            Dim dt As New DateTime(1900, 1, 1)
            Dim parsedDays = 0
            If Integer.TryParse(val.Value.RawValue, parsedDays) Then
                dt = dt.AddDays(parsedDays)
                selection.Worksheet.Cells(range.FromIndex.RowIndex, range.FromIndex.ColumnIndex).SetValue(dt.Year & "-" & MonthName(dt.Month))
            End If
        End If
    End Sub

        public class CustomGrid : RadGridView
        {
            public override string ThemeClassName
            {
                get
                {
                    return typeof(RadGridView).FullName;
                }
            }
            protected override void OnMouseDown(MouseEventArgs e)
            {
                GridExpanderItem expander = this.ElementTree.GetElementAtPoint(e.Location) as GridExpanderItem;
                if (expander != null)
                {
                    flag = true;
                }
                base.OnMouseDown(e);
            }

            protected override void OnMouseUp(MouseEventArgs e)
            {
                base.OnMouseUp(e);
                flag = false;
            }

            bool flag = false;

            protected override void OnPageChanging(object sender, PageChangingEventArgs e)
            {
                if (flag)
                {
                    e.Cancel = true;
                }
                base.OnPageChanging(sender, e);

            }
        }

private void RadGridView1_CreateRow(object sender, GridViewCreateRowEventArgs e)
{
    if (e.RowInfo is GridViewDetailsRowInfo)
    {
        e.RowElement = new MyGridDetailViewRowElement();
    }
}

public class MyGridDetailViewRowElement : GridDetailViewRowElement
{
    protected override SizeF MeasureOverride(SizeF availableSize)
    {
        var baseSize =  base.MeasureOverride(availableSize);
        if(baseSize.Width == float.PositiveInfinity)
        {
            baseSize.Width = 800;
        }
        return baseSize;
    }
}

        public RadForm1()
        {
            InitializeComponent();
            DataTable dt = new DataTable();
            dt.Columns.Add("DateOnly", typeof(DateOnly));
            dt.Rows.Add(new DateOnly(2022,3,3));

            this.radGridView1.AutoGenerateColumns = false;
            GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn();
            dateColumn.FieldName = "DateOnly";
            this.radGridView1.Columns.Add(dateColumn);
            this.radGridView1.DataSource = dt;
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
        }

        public RadForm1()
        {
            InitializeComponent();
            DataTable dt = new DataTable();
            dt.Columns.Add("DateOnly", typeof(DateOnly));
            dt.Rows.Add(new DateOnly(2022,3,3));

            this.radGridView1.AutoGenerateColumns = false;
            GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn();
            dateColumn.DataType = typeof(DateTime);
            dateColumn.FieldName = "DateOnly";
            dateColumn.Format = DateTimePickerFormat.Custom;
            dateColumn.CustomFormat = "dd/MM/yyyy";
            dateColumn.FormatString = "{0:dd/MM/yyyy}";
            dateColumn.DataTypeConverter = new DateOnlyConverter();
            this.radGridView1.Columns.Add(dateColumn);
            this.radGridView1.DataSource = dt;
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
        }


        public class DateOnlyConverter : TypeConverter
        {
            public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
            { 
                return destinationType == typeof(DateTime);
            }
            public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
            { 
                if (value is DateOnly && destinationType == typeof(DateTime))
                {
                    DateOnly date = (DateOnly)value;
                    return new DateTime(date.Year, date.Month, date.Day);
                }
                
                return base.ConvertTo(context, culture, value, destinationType);
            }
            public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
            { 
                return sourceType == typeof(DateTime) ;
            }
            public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
            { 
                if (value is DateTime)
                {
                    DateTime date = (DateTime)value;
                    return new DateOnly(date.Year, date.Month, date.Day);
                }
                
                return base.ConvertFrom(context, culture, value);
            }
        }

GridViewDataColumn column;

column.HeaderText = "Счет";

column.HeaderImage = ...; // some img

column.TextImageRelation = TextImageRelation.Overlay;

GridViewDataColumn column;

column.HeaderText = "";

column.HeaderImage = ...; // some img

column.TextImageRelation = TextImageRelation.Overlay;

            GridViewDateTimeColumn orderDate = this.radGridView1.Columns["OrderDate"] as GridViewDateTimeColumn;
            orderDate.Format = DateTimePickerFormat.Custom;
            orderDate.CustomFormat = "dd-MM-yyyy";
            orderDate.FormatString = "{0:dd-MM-yyyy}";


            GridViewDateTimeColumn shippedDate = this.radGridView1.Columns["ShippedDate"] as GridViewDateTimeColumn;
            shippedDate.Format = DateTimePickerFormat.Custom;
            shippedDate.CustomFormat = "dd-MM-yyyy";
            shippedDate.FormatString = "{0:dd-MM-yyyy}";

this.radGridView1.LoadLayout(@"..\..\..\Layout.xml");

<RadGridView Padding="0, 0, 0, 1" Cursor="Default" TabIndex="49">
<MasterTemplate EnableGrouping = "True" AllowEditRow="False" AllowDeleteRow="False" AllowAddNewRow="False" EnableFiltering="True" AutoExpandGroups="True">
<Columns>
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="JobID" Name="JobID" IsAutoGenerated="True" IsVisible="True" HeaderText="JobID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="CustomerID" Name="CustomerID" IsAutoGenerated="True" IsVisible="True" HeaderText="CustomerID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="285" FieldName="StatusID" Name="StatusID" IsAutoGenerated="True" IsVisible="True" HeaderText="StatusID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="UnitID" Name="UnitID" IsAutoGenerated="True" IsVisible="True" HeaderText="UnitID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="OperatorID" Name="OperatorID" IsAutoGenerated="True" IsVisible="True" HeaderText="OperatorID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="JobTypeID" Name="JobTypeID" IsAutoGenerated="True" IsVisible="True" HeaderText="JobTypeID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="JobCatID" Name="JobCatID" IsAutoGenerated="True" IsVisible="True" HeaderText="JobCatID" />
<Telerik.WinControls.UI.GridViewDateTimeColumn Width="100" FieldName="StartTime" Name="StartTime" IsAutoGenerated="True" IsVisible="True" HeaderText="StartTime">
<FilterDescriptor xsi:type="Telerik.WinControls.Data.DateFilterDescriptor" Value="" IgnoreTimePart="False" PropertyName="StartTime" Operator="IsNotNull" IsFilterEditor="True" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
</Telerik.WinControls.UI.GridViewDateTimeColumn>
<Telerik.WinControls.UI.GridViewDateTimeColumn Width="100" FieldName="FinishTime" Name="FinishTime" IsAutoGenerated="True" IsVisible="True" HeaderText="FinishTime" />
<Telerik.WinControls.UI.GridViewDateTimeColumn Width="100" FieldName="CreateDate" Name="CreateDate" SortOrder="Descending" IsAutoGenerated="True" IsVisible="True" HeaderText="CreateDate" />
<Telerik.WinControls.UI.GridViewDateTimeColumn Width="100" FieldName="StatusJobDate" Name="StatusJobDate" IsAutoGenerated="True" IsVisible="True" HeaderText="StatusJobDate" />
<Telerik.WinControls.UI.GridViewTextBoxColumn Width="100" FieldName="UserID" Name="UserID" IsAutoGenerated="True" IsVisible="True" HeaderText="UserID" />
<Telerik.WinControls.UI.GridViewTextBoxColumn DataType="System.Guid" Width="100" FieldName="TableKey" Name="TableKey" IsAutoGenerated="True" IsVisible="False" HeaderText="TableKey" />
</Columns>
<FilterDescriptors>
<Telerik.WinControls.Data.DateFilterDescriptor Value="" IgnoreTimePart="False" PropertyName="StartTime" Operator="IsNotNull" IsFilterEditor="True" />
</FilterDescriptors>
<SortDescriptors>
<Telerik.WinControls.Data.SortDescriptor PropertyName="CreateDate" Direction="Descending" />
</SortDescriptors>
<ViewDefinition xsi:type="Telerik.WinControls.UI.TableViewDefinition" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
</MasterTemplate>
</RadGridView>

public class CustomGridView : RadGridView
{
    protected override GridViewLayoutSerializer CreateGridViewLayoutSerializer(Telerik.WinControls.XmlSerialization.ComponentXmlSerializationInfo info)
    {
        return new CustomGridViewLayoutSerializer(info);
    }
    public override string ThemeClassName
    {
        get
        {
            return typeof(RadGridView).FullName;
        }
    }
}

public class CustomGridViewLayoutSerializer : GridViewLayoutSerializer
{ 
    public CustomGridViewLayoutSerializer(ComponentXmlSerializationInfo componentSerializationInfo) : base(componentSerializationInfo)
    {
    }

    protected override bool ProcessReaderAttribute(System.Xml.XmlReader reader, object parentObject, object toRead, PropertyDescriptor property)
    {
        if (toRead is FilterDescriptor && reader.Value == string.Empty)
        {
            object val = reader.Value;
            if (property.ComponentType == typeof(DateFilterDescriptor))
            {
                val = null;
            }
            
            this.SetPropertyValue(property, toRead, val);
            return true;
        }

        return base.ProcessReaderAttribute(reader, parentObject, toRead, property);
    }
}

        public RadForm1()
        {
            InitializeComponent();

            string txt = "what follows is test characters (some of) which should cause error:  เปลี่ยน UPS ที่ห้อง Truck scale เนื่องจากเมื่อวันพฤหัสที่ 13 มีการออฟเบรกเกอร์ที่ ฺฺB/H แต่ว่า เครื่องคอมพิวเตอร์ที่ T/S ดับ ตัว UPS ไม่ทำงาน ทำให้ข้อมูลขณะนั้นหายไป   ";
            this.label1.Text = txt; // No error

            Font font = this.label1.Font;// new Font("Segoe UI", 9.5f, FontStyle.Regular);
            this.radLabel1.Font = font;
            this.radLabel1.Text = txt; //GDI error
        }

this.radLabel1.UseCompatibleTextRendering = false;

public RadForm1()
{
    InitializeComponent();

    GridViewDecimalColumn idColumn = new GridViewDecimalColumn("Id");
    this.radGridView1.Columns.Add(idColumn);
    GridViewTextBoxColumn nameColumn = new GridViewTextBoxColumn("Name");
    this.radGridView1.Columns.Add(nameColumn);
    GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn("Date");
    dateColumn.FilteringMode = GridViewTimeFilteringMode.Date;
    dateColumn.Format = DateTimePickerFormat.Custom;
    dateColumn.CustomFormat = "dd/MM/yyyy";
    dateColumn.FormatString = "{0:dd/MM/yyyy}";
    this.radGridView1.Columns.Add(dateColumn);
    this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

    for (int i = 0; i < 50; i++)
    {
        this.radGridView1.Rows.Add(i,"Row"+i,DateTime.Now.AddDays(i));
    }

    this.radGridView1.EnableFiltering = true;
    this.radGridView1.ShowHeaderCellButtons = true;
    this.radGridView1.ShowFilteringRow = false;

    this.radGridView1.FilterExpressionChanged += RadGridView1_FilterExpressionChanged;
}

private void RadGridView1_FilterExpressionChanged(object sender, FilterExpressionChangedEventArgs e)
{
    Console.WriteLine(e.FilterExpression);
}

        private void RadGridView1_CreateCompositeFilterDialog(object sender, GridViewCreateCompositeFilterDialogEventArgs e)
        {
            e.Dialog = new CustomCompositeDataFilterForm();
        }

        public class CustomCompositeDataFilterForm : CompositeDataFilterForm
        {
            protected override void OnClosing(CancelEventArgs e)
            {
                base.OnClosing(e);
                if (GridFilterCellElement.ValidateUserFilter(this.FilterDescriptor))
                {
                    CompositeFilterDescriptor cfd = this.FilterDescriptor as CompositeFilterDescriptor;
                    if (cfd != null)
                    {
                        foreach (FilterDescriptor fd in cfd.FilterDescriptors)
                        {
                            TrimTimePart(fd);
                        }
                    }
                    else
                    {
                        TrimTimePart(this.FilterDescriptor);
                    }
                   
                }
            }

            private void TrimTimePart(FilterDescriptor filterDescriptor)
            {
                CompositeFilterDescriptor cfd = filterDescriptor as CompositeFilterDescriptor;
                if (cfd != null)
                {
                    foreach (FilterDescriptor fd in cfd.FilterDescriptors)
                    {
                        TrimTimePart(fd);
                    }
                }
                else
                {
                    DateTime dateValue = DateTime.MinValue;
                    if (DateTime.TryParse(filterDescriptor.Value + "", out dateValue))
                    {
                        dateValue = dateValue.Date;
                       filterDescriptor.Value = dateValue;
                    }
                }
            }
        }