To reproduce:

LineSeries lineSeries = new LineSeries();
lineSeries.DataPoints.Add(new CategoricalDataPoint(20, "Jan"));
lineSeries.DataPoints.Add(new CategoricalDataPoint(22, "Apr"));
lineSeries.DataPoints.Add(new CategoricalDataPoint(12, "Jul"));
lineSeries.DataPoints.Add(new CategoricalDataPoint(19, "Oct"));
lineSeries.LegendTitle = "Series A asdafsafasfd fgsdfg sdfs dfg dafsvsd";
this.radChartView1.Series.Add(lineSeries);
LineSeries lineSeries2 = new LineSeries();
lineSeries2.DataPoints.Add(new CategoricalDataPoint(18, "Jan"));
lineSeries2.DataPoints.Add(new CategoricalDataPoint(15, "Apr"));
lineSeries2.DataPoints.Add(new CategoricalDataPoint(17, "Jul"));
lineSeries2.DataPoints.Add(new CategoricalDataPoint(22, "Oct"));
lineSeries2.LegendTitle = "Series B sdf asdf adfasdfas dfadsf asdf sadf awef";
this.radChartView1.Series.Add(lineSeries2);
LineSeries lineSeries3 = new LineSeries();
lineSeries3.DataPoints.Add(new CategoricalDataPoint(13, "Jan"));
lineSeries3.DataPoints.Add(new CategoricalDataPoint(14, "Apr"));
lineSeries3.DataPoints.Add(new CategoricalDataPoint(12, "Jul"));
lineSeries3.DataPoints.Add(new CategoricalDataPoint(25, "Oct"));
lineSeries3.LegendTitle = "Series C sdf asdf adfasdfas dfadsf asdf sadf awef";
this.radChartView1.Series.Add(lineSeries3);

this.radChartView1.ShowLegend = true;
this.radChartView1.ChartElement.LegendPosition = Telerik.WinControls.UI.LegendPosition.Bottom;
radChartView1.ChartElement.LegendElement.StackElement.Orientation = Orientation.Horizontal;

Workaround: specify minimum height for the legend

radChartView1.ChartElement.LegendElement.MinSize = new Size(0, 50);

To reproduce:
LegendItem item = new LegendItem();
item.Element.BorderColor = Color.Black;
item.Element.BackColor = Color.Yellow;
item.Title = "Custom item";
this.radChartView1.ChartElement.LegendElement.Items.Add(item);

Workaround:
class MyLegendItem : LegendItem
{
    string title = "";
    protected override void SetLegendTitle(string title)
    {
        base.SetLegendTitle(title);
         
        if (this.Element is LegendItemStyleElement)
        {
            this.title = title;
        }
    }
    protected override string GetLegendTitle()
    {
        if (this.Element is LegendItemStyleElement)
        {
           return title;
        }
        return base.GetLegendTitle();

    }
}

To reproduce:
Add a RadChartView and use the following code:

public Form1()
{
    InitializeComponent();

    this.radChartView1.ShowTrackBall = true;
    this.radChartView1.ShowLegend = true;
    Random rand = new Random();
    var lineSeries = new LineSeries();
    for (int i = 0; i < 1000; i++)
    {
        lineSeries.DataPoints.Add(new CategoricalDataPoint(i, rand.Next(0, rand.Next(5, 20))));
    }
    radChartView1.Series.Add(lineSeries);
}

Workaround: change the LegendPosition:
this.radChartView1.ChartElement.LegendPosition = LegendPosition.Bottom;

To reproduce:

Public Sub New()
    InitializeComponent()

    Me.RadChartView1.ShowTitle = True
    Me.RadChartView1.ChartElement.TitleElement.TextWrap = True
    Me.RadChartView1.Title = "This is a very long chart title that can't fit in a single line"

    Dim barSeries As New BarSeries("Performance", "RepresentativeName")
    barSeries.Name = "Q1"
    barSeries.DataPoints.Add(New CategoricalDataPoint(177, "Harley"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(128, "White"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(143, "Smith"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(111, "Jones"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(118, "Marshall"))
    Me.RadChartView1.Series.Add(barSeries)
End Sub

Private Sub radButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click 
    Dim filePath As String = "..\..\..\exprtedChart.png"
    Me.RadChartView1.ExportToImage(filePath, Me.RadChartView1.Size, System.Drawing.Imaging.ImageFormat.Png)
    Process.Start(filePath)
End Sub


Workaround: titleSize must consider the chart's width

Public Sub New()
    InitializeComponent()
    AddHandler Me.RadChartView1.CreateRenderer, AddressOf CreateRenderer
    Me.RadChartView1.ShowTitle = True
    Me.RadChartView1.ChartElement.TitleElement.TextWrap = True
    Me.RadChartView1.Title = "This is a very long chart title that can't fit in a single line"

    Dim barSeries As New BarSeries("Performance", "RepresentativeName")
    barSeries.Name = "Q1"
    barSeries.DataPoints.Add(New CategoricalDataPoint(177, "Harley"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(128, "White"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(143, "Smith"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(111, "Jones"))
    barSeries.DataPoints.Add(New CategoricalDataPoint(118, "Marshall"))
    Me.RadChartView1.Series.Add(barSeries)
End Sub

Private Sub radButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click
    Dim filePath As String = "..\..\..\exprtedChart.png"
    Using fs As New FileStream(filePath, FileMode.Create, FileAccess.Write)
        ExportToImage(Me.RadChartView1, fs, Me.RadChartView1.Size, System.Drawing.Imaging.ImageFormat.Png)
    End Using
    Process.Start(filePath)
End Sub

Public Sub ExportToImage(chart As RadChartView, stream As Stream, size As Size, imageFormat As ImageFormat)
    If Not chart.IsLoaded Then
        chart.LoadElementTree()
    End If

    Dim bmp As New Bitmap(size.Width, size.Height)
    Dim graphics__1 As Graphics = Graphics.FromImage(bmp)
    graphics__1.Clear(Color.White)

    Dim titleSize As SizeF = graphics__1.MeasureString(chart.Title, chart.ChartElement.TitleElement.Font, chart.Width)

    If chart.ChartElement.TitleElement.TextOrientation = Orientation.Vertical Then
        Dim swap As Single = titleSize.Height
        titleSize.Height = titleSize.Width
        titleSize.Width = swap
    End If

    Dim titleRect As New RadRect(0, 0, titleSize.Width, titleSize.Height)
    Dim legendRect As New RadRect(0, 0, size.Width, size.Height)
    Dim chartRect As RadRect = legendRect

    Select Case chart.ChartElement.TitlePosition
        Case TitlePosition.Top, TitlePosition.Bottom
            titleRect.Width = size.Width
            Exit Select
        Case TitlePosition.Right, TitlePosition.Left
            titleRect.Height = size.Height
            Exit Select
    End Select

    chartRect.X += chart.View.Margin.Left
    chartRect.Y += chart.View.Margin.Top
    chartRect.Width -= chart.View.Margin.Horizontal
    chartRect.Height -= chart.View.Margin.Vertical

    If chart.ShowTitle Then
        Select Case chart.ChartElement.TitlePosition
            Case TitlePosition.Top
                legendRect.Y += titleRect.Height
                chartRect.Y += titleRect.Height
                legendRect.Height -= titleRect.Height
                chartRect.Height -= titleRect.Height
                Exit Select
            Case TitlePosition.Right
                titleRect.X = size.Width - chart.ChartElement.TitleElement.Size.Width
                titleRect.Height = size.Height
                legendRect.Width -= titleRect.Width
                chartRect.Width -= titleRect.Width
                Exit Select
            Case TitlePosition.Bottom
                titleRect.Y = size.Height - chart.ChartElement.TitleElement.Size.Height
                titleRect.Width = size.Width
                legendRect.Height -= titleRect.Height
                chartRect.Height -= titleRect.Height
                Exit Select
            Case TitlePosition.Left
                titleRect.Height = size.Height
                legendRect.X += titleRect.Width
                chartRect.X += titleRect.Width
                legendRect.Width -= titleRect.Width
                chartRect.Width -= titleRect.Width
                Exit Select
        End Select
    End If

    If chart.ShowLegend Then
        Select Case chart.ChartElement.LegendPosition
            Case LegendPosition.Right
                If chart.ChartElement.TitlePosition = TitlePosition.Right Then
                    legendRect.X = titleRect.X - chart.ChartElement.LegendElement.Size.Width
                Else
                    legendRect.X = size.Width - chart.ChartElement.LegendElement.Size.Width
                End If

                legendRect.Width = chart.ChartElement.LegendElement.Size.Width
                chartRect.Width -= legendRect.Width + chart.View.Margin.Right
                Exit Select
            Case LegendPosition.Bottom
                If chart.ChartElement.TitlePosition = TitlePosition.Bottom Then
                    legendRect.Y = titleRect.Y - chart.ChartElement.LegendElement.Size.Height
                Else
                    legendRect.Y = size.Height - chart.ChartElement.LegendElement.Size.Height
                End If

                legendRect.Height = chart.ChartElement.LegendElement.Size.Height
                chartRect.Height -= legendRect.Height
                Exit Select
            Case LegendPosition.Left
                legendRect.Width = chart.ChartElement.LegendElement.Size.Width
                chartRect.X += legendRect.Width + chart.View.Margin.Left
                chartRect.Width -= legendRect.Width + chart.View.Margin.Left
                Exit Select
            Case LegendPosition.Top
                legendRect.Height = chart.ChartElement.LegendElement.Size.Height
                chartRect.Y += legendRect.Height
                chartRect.Height -= legendRect.Height
                Exit Select
            Case LegendPosition.Float
                legendRect.Width = chart.ChartElement.LegendElement.Size.Width
                legendRect.Height = chart.ChartElement.LegendElement.Size.Height
                Dim xRatio As Double = size.Width / Me.Size.Width
                Dim yRatio As Double = size.Height / Me.Size.Height
                legendRect.X = (chart.ChartElement.LegendOffset.X * xRatio) + (If((chart.ChartElement.TitlePosition = TitlePosition.Left), titleRect.Right, 0.0))
                legendRect.Y = (chart.ChartElement.LegendOffset.Y * yRatio) + (If((chart.ChartElement.TitlePosition = TitlePosition.Top), titleRect.Bottom, 0.0F))
                Exit Select
        End Select
    End If

    If chart.ShowLegend Then
        Dim xTransform As Single = CSng(legendRect.X) - chart.ChartElement.LegendElement.ControlBoundingRectangle.X + _
        (CSng(legendRect.Width) - chart.ChartElement.LegendElement.ControlBoundingRectangle.Width) / 2.0F
        Dim yTransform As Single = CSng(legendRect.Y) - chart.ChartElement.LegendElement.ControlBoundingRectangle.Y + _
        (CSng(legendRect.Height) - chart.ChartElement.LegendElement.ControlBoundingRectangle.Height) / 2.0F
        graphics__1.TranslateTransform(xTransform, yTransform)
        chart.ChartElement.LegendElement.Paint(New RadGdiGraphics(graphics__1), _
                                               chart.ChartElement.LegendElement.ControlBoundingRectangle, 0.0F, New SizeF(1.0F, 1.0F), True)
        graphics__1.ResetTransform()
    End If

    Dim radGraphics As New RadGdiGraphics(graphics__1)

    If chart.ShowTitle Then
        radGraphics.DrawString(chart.Title, GetTitleDrawRectangle(ChartRenderer.ToRectangleF(titleRect), _
                                                                  titleSize, chart.ChartElement.TitleElement.TextAlignment), chart.ChartElement.TitleElement.Font, _
                               chart.ChartElement.TitleElement.ForeColor, chart.ChartElement.TitleElement.TextParams.CreateStringFormat(), _
                               chart.ChartElement.TitleElement.TextOrientation, _
                               chart.ChartElement.TitleElement.FlipText)
    End If

    chart.View.Layout(chartRect)
    renderer.Draw(graphics__1)

    bmp.Save(stream, imageFormat)
    chart.View.Layout()
End Sub

Private Function GetTitleDrawRectangle(drawArea As RectangleF, textRect As SizeF, textAlignment As ContentAlignment) As RectangleF
    Select Case textAlignment
        Case ContentAlignment.BottomCenter
            Return New RectangleF(New PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2.0F, drawArea.Bottom - textRect.Height), textRect)
        Case ContentAlignment.BottomLeft
            Return New RectangleF(New PointF(drawArea.X, drawArea.Bottom - textRect.Height), textRect)
        Case ContentAlignment.BottomRight
            Return New RectangleF(New PointF(drawArea.Right - textRect.Width, drawArea.Bottom - textRect.Height), textRect)
        Case ContentAlignment.MiddleCenter
            Return New RectangleF(New PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2.0F, drawArea.Y + (drawArea.Height - textRect.Height) / 2.0F), textRect)
        Case ContentAlignment.MiddleLeft
            Return New RectangleF(New PointF(drawArea.X, drawArea.Y + (drawArea.Height - textRect.Height) / 2.0F), textRect)
        Case ContentAlignment.MiddleRight
            Return New RectangleF(New PointF(drawArea.Right - textRect.Width, drawArea.Y + (drawArea.Height - textRect.Height) / 2.0F), textRect)
        Case ContentAlignment.TopCenter
            Return New RectangleF(New PointF(drawArea.X + (drawArea.Width - textRect.Width) / 2, drawArea.Y), textRect)
        Case ContentAlignment.TopLeft
            Return New RectangleF(drawArea.Location, textRect)
        Case ContentAlignment.TopRight
            Return New RectangleF(New PointF(drawArea.Right - textRect.Width, drawArea.Y), textRect)
        Case Else
            Return New RectangleF(drawArea.Location, textRect)
    End Select
End Function

Dim renderer As CartesianRenderer
Private Sub CreateRenderer(sender As Object, e As ChartViewCreateRendererEventArgs)
    e.Renderer = New CartesianRenderer(DirectCast(e.Area, CartesianArea))
    renderer = e.Renderer
End Sub

Steps to reproduce: 
1. Add RadChartView with two BarSeries 
2. Set the Name property of series 
3. Set the SelectionMode property to SingleDataPoint
4. Subscribe to the SelectedPointChanging/SelectedPointChanged events. 
5. Run the form and select points from different series. The OldSelectedSeries/NewSelectedSeries properties always return the name of the first series now matter which series is selected. 

Workaround: 
void radChartView1_SelectedPointChanged(object sender, ChartViewSelectedPointChangedEventArgs e)
{
    BarSeries series = (e.NewSelectedPoint).Presenter as BarSeries;

    if (series.Name == "Q1")
    {
        Console.WriteLine(series.Name);
    }
    else if (series.Name == "Q2")
    {
        Console.WriteLine(series.Name);
    }
}

Introduce gantt like series as in RadChart: http://docs.telerik.com/devtools/winforms/chart/understanding-radchart-types/gantt-charts 

so that Y increases as you move down the screen. (Even) microsoft chart component supports this. 

To reproduce: use the following code snippet
public Form1()
{
    InitializeComponent();

    ScatterLineSeries scatterSeries = new ScatterLineSeries();
    scatterSeries.DataPoints.Add(new ScatterDataPoint(15, 19));
    scatterSeries.DataPoints.Add(new ScatterDataPoint(18, 10));
    scatterSeries.DataPoints.Add(new ScatterDataPoint(13, 15));
    scatterSeries.DataPoints.Add(new ScatterDataPoint(10, 8));
    scatterSeries.DataPoints.Add(new ScatterDataPoint(5, 2));
    scatterSeries.PointSize = new SizeF(8, 8);
    this.radChartView1.Series.Add(scatterSeries);

    ScatterLineSeries scatterSeries2 = new ScatterLineSeries();
    scatterSeries2.DataPoints.Add(new ScatterDataPoint(2, 24));
    scatterSeries2.DataPoints.Add(new ScatterDataPoint(7, 12));
    scatterSeries2.DataPoints.Add(new ScatterDataPoint(15, 10));
    scatterSeries2.DataPoints.Add(new ScatterDataPoint(18, 22));
    scatterSeries2.DataPoints.Add(new ScatterDataPoint(20, 20));
    scatterSeries2.Shape = new RoundRectShape(1);
    scatterSeries2.PointSize = new SizeF(8, 8);
    this.radChartView1.Series.Add(scatterSeries2);
    
    ChartTooltipController toolTipController = new ChartTooltipController();
   
    radChartView1.Controllers.Add(toolTipController); 
}

Workaround: use custom renderer

public Form1()
{
    InitializeComponent();

    this.radChartView1.CreateRenderer += radChartView1_CreateRenderer;
}
private void radChartView1_CreateRenderer(object sender, ChartViewCreateRendererEventArgs e)
{
    e.Renderer = new CustomCartesianRenderer(e.Area as CartesianArea);
}

public class CustomCartesianRenderer : CartesianRenderer
{
    public CustomCartesianRenderer(CartesianArea area) : base(area)
    {
    }
    
    protected override void Initialize()
    {
        base.Initialize();

        for (int i = 0; i < this.DrawParts.Count; i++)
        {
            ScatterSeriesDrawPart scatterPart = this.DrawParts[i] as ScatterSeriesDrawPart;
            if (scatterPart != null)
            {
                this.DrawParts[i] = new CustomScatterSeriesDrawPart((ScatterLineSeries)scatterPart.Element, this);
            }
        }
    }
}

public class CustomScatterSeriesDrawPart : ScatterLineSeriesDrawPart
{
    public CustomScatterSeriesDrawPart(ScatterLineSeries series, IChartRenderer renderer) 
        : base(series, renderer)
    {
    }

    public override DataPoint HitTest(Point location)
    {
        for (int i = 0; i < this.Element.DataPoints.Count; i++)
        {
            RadRect slot = this.Element.DataPoints[i].LayoutSlot;
            float pointHalfWidth = this.Element.PointSize.Width / 2;
            float pointHalfHeight = this.Element.PointSize.Height / 2;

            RectangleF scatterBounds = new RectangleF((float)(this.OffsetX + slot.X - pointHalfWidth),
                (float)(this.OffsetY + slot.Y - pointHalfHeight), this.Element.PointSize.Width, this.Element.PointSize.Height);

            if (scatterBounds.Contains(location.X, location.Y))
            {
                return this.Element.DataPoints[i];
            }
        }

        return null;
    }
}

To reproduce:


You need a RadChartView with some series. You need to add a new View - 


radChartView1.Views.AddNew("Bigger");


You also need to add a DrillDownController:


DrillDownController drillcontrol = new DrillDownController();
radChartView1.Controllers.Add(drillcontrol);
radChartView1.ShowDrillNavigation = true;


On the Drill event of RadChartView you need to reload the chart. This must clear the axes on the current view (determined by the drill level) and add new ones. You will see that the legend will not update. 


Additional details can be found in the attached project.


Workaround:


Re-add the legend items manually:


private void radChartView1_Drill(object sender, DrillEventArgs e)
{
    if (e.Level == 0)
        BiggerView = false;
    else
        BiggerView = true;


    ReloadChart();

    this.radChartView1.ChartElement.LegendElement.StackElement.Children.Clear();
    ChartView currentView = this.radChartView1.Views[BiggerView ? 1 : 0];
    foreach (ChartSeries series in currentView.Series)
    {
        LegendItem item = new LegendItem(series)
        {
            Title = series.Name
        };


        LegendItemElement element = new LegendItemElement(item);
        this.radChartView1.ChartElement.LegendElement.StackElement.Children.Add(element);
    }
}

How can I achieve the same behaviour as with the obsolete RadChart plotting the area between the maxima of a sine. 

With significant number of points in pie series and with very small values as data points, the default chart strategy for positioning smart labels overlaps the values.

Note: the smart labels overlapping can be reproduced with DonutSeries as well.

To reproduce:

Use the following code with RadChartView: 

this.Chart.Series.Add(new LineSeries());


for (int i = 0; i < 50; i++)
{
    if (i == 10)
    {
        this.Chart.Series[0].DataPoints.Add(new CategoricalDataPoint(1));
        continue;
    }


    this.Chart.Series[0].DataPoints.Add(new CategoricalDataPoint(0));
}

this.Chart.ShowGrid = true;

You will see that the point will not be rendered correctly and will be taller than 1.

Add the ability a user to be able to use a Custom DashStyle in the following scenario:

this.Chart.ShowLegend = true;
this.Chart.Series.Add(new LineSeries() { LegendTitle = "DDDD" });
this.Chart.ChartElement.LegendElement.Items[0].Element.BorderDashStyle = System.Drawing.Drawing2D.DashStyle.Custom;

for (int i = 0; i < 10; i++)
{
    this.Chart.Series[0].DataPoints.Add(i);
}

The following article describes how to use a Custom DashStyle: How to: Draw a Custom Dashed Line

To reproduce:

Setup the following RadChartView:

this.Chart.ShowLegend = true;
this.Chart.Series.Add(new LineSeries() { LegendTitle = "DDDD" });
this.Chart.ChartElement.LegendElement.Items[0].Element.BorderDashStyle = System.Drawing.Drawing2D.DashStyle.DashDotDot;


for (int i = 0; i < 10; i++)
{
    this.Chart.Series[0].DataPoints.Add(i);
}


You will see that although that you have changed the BorderDashStyle of the Element, the LineSerie will be drawn normally.

When one adds data points with negative and positive values, the negative ones should go below the 0, for example, with the following data:

AreaSeries areaSeries = new AreaSeries();
areaSeries.DataPoints.Add(new CategoricalDataPoint(5, "Jan"));
areaSeries.DataPoints.Add(new CategoricalDataPoint(-10, "Apr"));

Resolution: 
To use the functionality one should set the StartPositionAxis and StartPositionValue properties of an axis. The first property is the axis along which the current axis will be aligned. The second is the value where the current axis should be positioned.
Here is a sample code: 
AreaSeries areaSeries = new AreaSeries();
areaSeries.DataPoints.Add(new CategoricalDataPoint(13, "Jan"));
areaSeries.DataPoints.Add(new CategoricalDataPoint(20, "Apr"));
areaSeries.DataPoints.Add(new CategoricalDataPoint(-15, "Jul"));
areaSeries.DataPoints.Add(new CategoricalDataPoint(16, "Oct"));
this.radChartView1.Series.Add(areaSeries);

areaSeries.HorizontalAxis.StartPositionAxis = areaSeries.VerticalAxis;
areaSeries.HorizontalAxis.StartPositionValue = 0;