public class CustomRadDropDownButtonElement : RadDropDownButtonElement
{
    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(RadDropDownButtonElement);
        }
    }
    protected override RadDropDownButtonPopup CreateDropDown()
    {
        return new CustomDropDown(this);
    }
}

public class CustomDropDown : RadDropDownButtonPopup
{
    public CustomDropDown(RadElement ownerElement) : base(ownerElement)
    {
    }

    protected override void EnsureItemEnabled(RadItem item, bool isUp)
    {
        do
        {
            item = this.GetNextItem(item, !isUp);
            if (item == this.Items.Last())
            {
                break;
            }

        } while (!item.Enabled);
        if (item != null)
        {

            this.SelectItem(item);
        }
    }
}

    internal static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            RadControl.EnableRadAutoScale = true;
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);


            string text = "Are you sure you want to exit?";
            string caption = "Application";
            RadMessageIcon icon = RadMessageIcon.Question;
            RadMessageBox.Show(text, caption, MessageBoxButtons.YesNo, icon);

            RadMessageBox.Show(text, caption, MessageBoxButtons.YesNoCancel, icon); 
       

RadControl.EnableRadAutoScale = false;

radRichTextEditor1.ChangeFontStyle( FontStyle.Underline);

radRichTextEditor1.ToggleUnderline();

        private void RadTimePicker1_ValueChanged(object sender, EventArgs e)
        {
            this.radTimePicker1.TimePickerElement.PopupContentElement.ClockElement.Value = this.radTimePicker1.Value;
        }

public partial class RadForm1 : Telerik.WinControls.UI.RadForm
    {
        public RadForm1()
        {
            InitializeComponent();
            DataTable dt = new DataTable();
            for (int i = 0; i < 20; i++)
            {
                dt.Columns.Add("col" + i, typeof(string));
            }
            for (int i = 0; i < 10; i++)
            {
                DataRow r = dt.NewRow();
                foreach (DataColumn col in dt.Columns)
                {
                    r[col.ColumnName] = Guid.NewGuid().ToString();
                }
                dt.Rows.Add(r);
            }
            this.radFilterView1.DataSource = dt;
          
        }


        private void radFilterView1_CategoryCreated(object sender, Telerik.WinControls.UI.FilterView.FilterViewCategoryCreatedEventArgs e)
        {
            e.Category.ExpandedChanged += Category_ExpandedChanged;
            e.Category.Expanded = false;

        }

        private void Category_ExpandedChanged(object? sender, EventArgs e)
        {
            // You need pass the control to Windows main loop to perform the pending telerik events after property Expanded change in order to resize internally
            // the StackLayoutPanel Containers before calling UpdateScrollBars
            Application.DoEvents();
            // Now your code
            MethodInfo mi = typeof(RadFilterViewElement).GetMethod("UpdateScrollbars", BindingFlags.Instance | BindingFlags.NonPublic);
            mi.Invoke(this.radFilterView1.FilterViewElement, new object[] { this.radFilterView1.FilterViewElement.ElementsPanel.Size });
            // Hide the horizontal scrolll bar
            radFilterView1.FilterViewElement.HorizontalScrollBar.Visibility =ElementVisibility.Collapsed;
        }

    }

        public RadForm1()
        {
            InitializeComponent();

             DataTable dt = new DataTable();
            for (int i = 0; i < 20; i++)
            {
                dt.Columns.Add("col" + i, typeof(string));
            }
            for (int i = 0; i < 10; i++)
            {
                DataRow r = dt.NewRow();
                foreach (DataColumn col in dt.Columns)
                {
                    r[col.ColumnName] = Guid.NewGuid().ToString();
                }
                dt.Rows.Add(r);
            }
            this.radFilterView1.DataSource = dt;
        }

        protected override void OnShown(EventArgs e)
        {
            base.OnShown(e); 
            MethodInfo mi = typeof(RadFilterViewElement).GetMethod("UpdateScrollbars", BindingFlags.Instance | BindingFlags.NonPublic);
            mi.Invoke(this.radFilterView1.FilterViewElement, new object[] { this.radFilterView1.FilterViewElement.ElementsPanel.Size });
        }

        private void radFilterView1_CategoryCreated(object sender, Telerik.WinControls.UI.FilterView.FilterViewCategoryCreatedEventArgs e)
        {
            e.Category.ExpandedChanged += Category_ExpandedChanged;
            e.Category.Expanded = false;

        }

        private void Category_ExpandedChanged(object? sender, EventArgs e)
        {
            // You need pass the control to Windows main loop to perform the pending telerik events after property Expanded change in order to resize internally
            // the StackLayoutPanel Containers before calling UpdateScrollBars
            Application.DoEvents();
            // Now your code
            MethodInfo mi = typeof(RadFilterViewElement).GetMethod("UpdateScrollbars", BindingFlags.Instance | BindingFlags.NonPublic);
            mi.Invoke(this.radFilterView1.FilterViewElement, new object[] { this.radFilterView1.FilterViewElement.ElementsPanel.Size });
            // Hide the horizontal scrolll bar
            radFilterView1.FilterViewElement.HorizontalScrollBar.Visibility =ElementVisibility.Collapsed;
        }

    Sub New() 
        InitializeComponent()

        Me.CommandBarButton1.Name = "MoveFirstItem"
        Me.CommandBarButton2.Name = "MovePreviousItem"
        Me.CommandBarTextBox1.Name = "PositionItem"
        Me.CommandBarLabel1.Name = "CountItem"
        Me.CommandBarButton3.Name = "MoveNextItem"
        Me.CommandBarButton4.Name = "MoveLastItem"
        Me.CommandBarButton5.Name = "AddNewItem"
        Me.CommandBarButton6.Name = "DeleteItem"
        Me.CommandBarStripElement2.DisplayName = "SecondStrip"
        Me.CommandBarStripElement1.DisplayName = "FirstStrip"

    End Sub

        public RadForm1()
        {
            InitializeComponent();

                        // This XML contains a simple tree with a root node having 3 children, the first of which is intended to be Bold
            var xml = "<TreeView xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" MultiSelect=\"true\" AllowDragDrop=\"true\" LabelEdit=\"true\" AllowDrop=\"true\">  <Nodes Text=\"New Package\" Expanded=\"true\" ImageKey=\"Package\" Font=\"Microsoft Sans Serif, 8.25pt, style=Bold\">    <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\New Package&lt;/FullName&gt;&lt;ObjectType&gt;Package&lt;/ObjectType&gt;&lt;IsRunnable&gt;False&lt;/IsRunnable&gt;&lt;IsContainer&gt;true&lt;/IsContainer&gt;&lt;/Info&gt;</Tag>    <Nodes Text=\"Query Engine\" ImageKey=\"QueryEngine\" Expanded=\"true\" Font=\"Microsoft Sans Serif, 8.25pt, style=Bold\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Query Engine&lt;/FullName&gt;&lt;ObjectType&gt;QueryEngine&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector\" ImageKey=\"Irion.SQLServer\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector&lt;/FullName&gt;&lt;ObjectType&gt;DBConnection&lt;/ObjectType&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector Link\" ImageKey=\"DatabaseDatalink\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector Link&lt;/FullName&gt;&lt;ObjectType&gt;DatabaseDatalink&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>  </Nodes></TreeView>";

            this.radTreeView1.LoadXML(new MemoryStream(System.Text.Encoding.UTF8.GetBytes(xml)));

            //make sure that the following 2 nodes are bold:
            this.radTreeView1.Nodes[0].Nodes[0].Font = new Font("Microsoft Sans Serif", 8.25F, FontStyle.Bold, GraphicsUnit.Point, 0);
            this.radTreeView1.Nodes[0].Nodes[2].Font = new Font("Microsoft Sans Serif", 8.25F, FontStyle.Bold, GraphicsUnit.Point, 0);

            var tvx = this.radTreeView1.TreeViewXml;
        }

    Public Sub New()
        InitializeComponent()

        allTimeZones = SchedulerTimeZone.GetSchedulerTimeZones()
        Dim mumbai As SchedulerTimeZone = GetSpecificTimeZone("India Standard Time")
        If Not mumbai.Equals(Me.RadScheduler1.GetDayView().DefaultTimeZone) Then
            RadScheduler1.GetDayView().TimeZones.Insert(0, mumbai)
        End If

        Dim utc As SchedulerTimeZone = GetSpecificTimeZone("UTC")
        If Not utc.Equals(Me.RadScheduler1.GetDayView().DefaultTimeZone) Then
            RadScheduler1.GetDayView().TimeZones.Insert(0, utc)
        End If
    End Sub
    Private Function GetSpecificTimeZone(_TimeZoneInformationID As String) As SchedulerTimeZone
        Try
            Dim tempZone As New SchedulerTimeZone((From t In allTimeZones.Where(Function(x) x.TimeZoneInformation.Id Like _TimeZoneInformationID) Select t.TimeZoneInformation).First)
            tempZone.Label = tempZone.TimeZoneInformation.BaseUtcOffset.ToString()
            Return tempZone
        Catch ex As Exception
            Return Nothing
        End Try
    End Function

Public Class Form1

    Private allTimeZones As List(Of SchedulerTimeZone)

    Public Sub New()
        InitializeComponent()

        Me.RadScheduler1.ElementProvider = New CustomSchedulerElementProvider(Me.RadScheduler1)


        allTimeZones = SchedulerTimeZone.GetSchedulerTimeZones()
        Dim mumbai As SchedulerTimeZone = GetSpecificTimeZone("India Standard Time")
        If Not mumbai.Equals(Me.RadScheduler1.GetDayView().DefaultTimeZone) Then
            RadScheduler1.GetDayView().TimeZones.Insert(0, mumbai)
        End If

        Dim utc As SchedulerTimeZone = GetSpecificTimeZone("UTC")
        If Not utc.Equals(Me.RadScheduler1.GetDayView().DefaultTimeZone) Then
            RadScheduler1.GetDayView().TimeZones.Insert(0, utc)
        End If
    End Sub
    Private Function GetSpecificTimeZone(_TimeZoneInformationID As String) As SchedulerTimeZone
        Try
            Dim tempZone As New SchedulerTimeZone((From t In allTimeZones.Where(Function(x) x.TimeZoneInformation.Id Like _TimeZoneInformationID) Select t.TimeZoneInformation).First)
            tempZone.Label = tempZone.TimeZoneInformation.BaseUtcOffset.ToString()
            Return tempZone
        Catch ex As Exception
            Return Nothing
        End Try
    End Function
End Class

Public Class CustomSchedulerElementProvider
        Inherits SchedulerElementProvider

        Public Sub New(scheduler As RadScheduler)
            MyBase.New(scheduler)
        End Sub

        Public Overrides Function CreateRulerPrimitive(area As DayViewAppointmentsArea, timeZone As SchedulerTimeZone) As RulerPrimitive
            Dim ruler As RulerPrimitive = MyBase.CreateRulerPrimitive(area, timeZone)
            ruler.RulerRenderer = New CustomRulerRenderer(ruler)
            Return ruler
        End Function
    End Class

Public Class CustomRulerRenderer
    Inherits RulerRenderer


    Public Sub New(ruler As RulerPrimitive)
        MyBase.New(ruler)
    End Sub

    Public Overrides Sub RenderHour(g As IGraphics, hour As Integer, bounds As RectangleF)
        hour += Me.ruler.StartScale + CInt(Math.Ceiling(Me.ruler.DefaultOffset))
        Dim currentTime As DateTime = DateTime.Now.Date.AddHours(hour)
        Dim percent As Single = Me.ruler.DefaultOffset - CSng(Math.Floor(CDbl(Me.ruler.DefaultOffset)))
        Dim x As Integer = Me.ruler.HourLineStartPosition
        Dim y As Single = CSng(Math.Ceiling(bounds.Top + (GetSpecificRange() * bounds.Height) * percent))
        Dim hourText As String = ""

        If Me.ruler.FormatStrings.HoursFormatString IsNot Nothing Then
            hourText = currentTime.ToString(Me.ruler.FormatStrings.HoursFormatString)
        End If

        'Dim args As RulerTextFormattingEventArgs = New RulerTextFormattingEventArgs(hourText, RulerTextFormattingContext.Hour, currentTime)
        'Me.ruler.Scheduler.OnRulerTextFormatting(args)
        'hourText = args.Text
        Dim minutesText As String = ""

        If Me.ruler.FormatStrings.MinutesFormatString IsNot Nothing Then
            minutesText = currentTime.ToString(Me.ruler.FormatStrings.MinutesFormatString)
        End If

        'args = New RulerTextFormattingEventArgs(minutesText, RulerTextFormattingContext.Minute, currentTime)
        'Me.ruler.scheduler.OnRulerTextFormatting(args)
        'minutesText = args.Text
        Dim measuredSize As Size = TextRenderer.MeasureText(hourText, Me.ruler.Font)
        measuredSize = DrawTimeText(g, y, hourText, minutesText, measuredSize)

        If ruler.RightToLeft Then
            g.DrawLine(Me.ruler.HourLineColor, Me.ruler.Bounds.Left, y, Me.ruler.Bounds.Width - x, y, Me.ruler.DpiScaleFactor.Height)
            g.DrawLine(Me.ruler.HourLineShadowColor, Me.ruler.Bounds.Left, y + Me.ruler.DpiScaleFactor.Height, Me.ruler.Bounds.Width - x, y + Me.ruler.DpiScaleFactor.Height, Me.ruler.DpiScaleFactor.Height)
        Else
            g.DrawLine(Me.ruler.HourLineColor, x, y, Me.ruler.Bounds.Width, y, Me.ruler.DpiScaleFactor.Height)
            g.DrawLine(Me.ruler.HourLineShadowColor, x, y + Me.ruler.DpiScaleFactor.Height, Me.ruler.Bounds.Width, y + Me.ruler.DpiScaleFactor.Height, Me.ruler.DpiScaleFactor.Height)
        End If
    End Sub

    Friend Function GetSpecificRange() As Integer
        Return 60 / CInt(Me.ruler.RangeFactor)
    End Function
End Class

        public RadForm1()
        {
            InitializeComponent();
            this.radGridView1.Columns.Add("TextColumn");
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

            for (int i = 0; i < 30; i++)
            {
                this.radGridView1.Rows.Add(Guid.NewGuid().ToString());
            }
            this.radGridView1.CellValidating += radGridView1_CellValidating;

            this.radGridView1.EditorManager.CloseEditorWhenValidationFails = false;
        }

        private void radGridView1_CellValidating(object sender, CellValidatingEventArgs e)
        {
            if (e.Value == null || e.Value == "")
            {
                e.Cancel = true;
                RadMessageBox.Show("Value can't be empty!");
            }
        }

        public class MyGrid : RadGridView
        {
            public override string ThemeClassName
            {
                get
                {
                    return typeof(RadGridView).FullName;
                }
            }

            protected override void OnMouseDown(MouseEventArgs e)
            {
                RadScrollBarElement scrollBarAtPoint = GetScrollbarElementAtPoint<RadScrollBarElement>(this.GridViewElement.ElementTree, e.Location) as RadScrollBarElement;
                GridViewEditManager editManager = this.EditorManager;
                if (scrollBarAtPoint != null && this.ActiveEditor != null && !editManager.CloseEditorWhenValidationFails)
                {
                    bool isClosed = editManager.CloseEditor();
                    if (!isClosed)
                    {
                        return;
                    }
                }
                base.OnMouseDown(e);
            }

            internal T GetScrollbarElementAtPoint<T>(RadElementTree componentTree, Point point) where T : RadElement
            {
                if (componentTree != null)
                {
                    RadElement elementUnderMouse = componentTree.GetElementAtPoint(point);

                    while (elementUnderMouse != null)
                    {
                        T item = elementUnderMouse as T;

                        if (item != null)
                        {
                            return item;
                        }

                        elementUnderMouse = elementUnderMouse.Parent;
                    }
                }

                return null;
            }
        }

var xml = "<TreeView xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" MultiSelect=\"true\" AllowDragDrop=\"true\" LabelEdit=\"true\" AllowDrop=\"true\">  <Nodes Text=\"New Package\" Expanded=\"true\" ImageKey=\"Package\" Font=\"Microsoft Sans Serif; 8,25pt; style=Bold\">    <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\New Package&lt;/FullName&gt;&lt;ObjectType&gt;Package&lt;/ObjectType&gt;&lt;IsRunnable&gt;False&lt;/IsRunnable&gt;&lt;IsContainer&gt;true&lt;/IsContainer&gt;&lt;/Info&gt;</Tag>    <Nodes Text=\"Query Engine\" ImageKey=\"QueryEngine\" Expanded=\"true\" Font=\"Microsoft Sans Serif; 8,25pt; style=Bold\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Query Engine&lt;/FullName&gt;&lt;ObjectType&gt;QueryEngine&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector\" ImageKey=\"Irion.SQLServer\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector&lt;/FullName&gt;&lt;ObjectType&gt;DBConnection&lt;/ObjectType&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector Link\" ImageKey=\"DatabaseDatalink\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector Link&lt;/FullName&gt;&lt;ObjectType&gt;DatabaseDatalink&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>  </Nodes></TreeView>";

        public RadForm1()
        {
            InitializeComponent();

            this.radWebCam1.AutoStart = false; 
        }

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

            ReadOnlyCollection<MediaFoundationDeviceInfo> videoDevices = RadWebCam.GetVideoCaptureDevices();
            ReadOnlyCollection<MediaFoundationVideoFormatInfo> videoFormats = RadWebCam.GetVideoFormats(videoDevices[0], true);
            ReadOnlyCollection<MediaFoundationDeviceInfo> audioDevices = RadWebCam.GetAudioCaptureDevices();

            radWebCam1.Initialize(videoDevices[0], videoFormats[0], audioDevices[0]);
        }

        protected override void OnShown(EventArgs e)
        {
            base.OnShown(e);
           
            radWebCam1.Start();       
        }