Workaround: use the ChartTrackerballController.TextNeeded event.

To reproduce:
- Implement the drill down functionality with a PieSeries.

- Workaround:
class MyPieSeries : PieSeries, ILegendInfoProvider
{
    public LegendItemCollection LegendInfos
    {
        get
        {
            return new LegendItemCollection();
        }
    }
}

To reproduce:
-  Show the legend and the add remove series at runtime.
- The legend items must not have text.
 

To reproduce:
- Add three line series and only set their point size.
- At runtime remove the second series.
- The points color is not updated corectly.

Workaround
- Set colors in code like this:
lineSerie1.BorderColor = Color.Red;
lineSerie1.BackColor = Color.Red;

lineSerie2.BackColor = Color.Green;
lineSerie2.BorderColor = Color.Green;

lineSerie3.BackColor = Color.Blue;
lineSerie3.BorderColor = Color.Blue;

To reproduce: 
1. Add RadChartView with drill down and two RadCheckBox on the form
2. Subscribe to the ToggleStateChanged event of RadCheckBox and set the IsVisible property to true/false 
3. In handler of DrillDown event set the series`s IsVisible property to be equal to checkbox`s Checked property
4. In few cases the series are not visible when changing the IsVisible property and view. 

Unfortunately due to the nature of the issue we cannot provide a workaround for it. 

To reproduce:
- Subscribe to the SelectedPointChanged event and show a dialog in it.
- Start the chart and zoom in. Select a point, close the dialog and select a point again.

Workaround:
class MyChartSelectionController : ChartSelectionController
{
    protected override ActionResult OnMouseDown(MouseEventArgs e)
    {
        //return base.OnMouseDown(e);
        return Controller.Empty;
    }
    protected override ActionResult OnMouseUp(MouseEventArgs e)
    {
        if (!this.AllowSelect || this.SelectionMode == ChartSelectionMode.None)
        {
            return base.OnMouseUp(e);
        }

        DataPoint oldDataPoint = SelectedPoint;
        DataPoint newDataPoint = null;
        ChartSeries oldSeries = SelectedSeries;
        ChartSeries newSeries = null;
        DataPoint point = null;

        foreach (ChartSeries series in this.Area.Series)
        {
            point = series.HitTest(e.X, e.Y);
            if (point != null)
            {
                newDataPoint = point;
                newSeries = series;
                break;
            }
        }

        if (point == null)
        {
            return base.OnMouseUp(e);
        }

        ChartViewSelectedPointChangingEventArgs cancelArgs = new ChartViewSelectedPointChangingEventArgs(oldDataPoint, newDataPoint, oldSeries, newSeries, this.SelectionMode);
        OnSelectedPointChanging(cancelArgs);

        if (cancelArgs.Cancel == true)
        {
            return base.OnMouseUp(e);
        }

        if (oldDataPoint == newDataPoint)
        {
            oldDataPoint.IsSelected = !oldDataPoint.IsSelected;
            newDataPoint = null;
            SelectedPoint = null;
        }
        else
        {
            if (this.SelectionMode == ChartSelectionMode.SingleDataPoint && oldDataPoint != null)
            {
                oldDataPoint.IsSelected = false;
            }

            this.SelectedPoint = newDataPoint;
            this.SelectedPoint.IsSelected = !SelectedPoint.IsSelected;
        }

        ChartViewSelectedPointChangedEventArgs changedArgs = new ChartViewSelectedPointChangedEventArgs(oldDataPoint, newDataPoint, oldSeries, newSeries, this.SelectionMode);
        OnSelectedPointChanged(changedArgs);
    
        return base.OnMouseUp(e);
    }

   
}

To reproduce:
- Add a pie chart using the property builder and set the palette as well.

Workaround
- Set the palette in code:
 this.radChartView1.Area.View.Palette = KnownPalette.Metro;

To reproduce:
this.radChartView1.AreaType = ChartAreaType.Pie;
PieSeries series = new PieSeries();

series.DataPoints.Add(new PieDataPoint(50, "Germany"));

series.DataPoints.Add(new PieDataPoint(70, "United States"));

series.DataPoints.Add(new PieDataPoint(40, "France"));

for (int i = 0; i < 50; i++)
{
    series.DataPoints.Add(new PieDataPoint(1, "Item " + i));
}

series.ShowLabels = true;
series.DrawLinesToLabels = true;
this.radChartView1.Series.Add(series);
 this.radChartView1.ShowSmartLabels = true;

How to reproduce: create a drill down chart with different area types on the different levels. 
The issue seems to be related to some series not implementing the ILegendInfoProvider interface.

Workaround:
A similar result as having a drill-down chart with series having different area types can be achieved manually using the ChartSelectionController. Please check the attached project and video file.

To reproduce:
public RadForm1()
{
    InitializeComponent();

    LineSeries lineSeries = new LineSeries();
    lineSeries.DataPoints.Add(new CategoricalDataPoint(40, "Jan"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(22, "Apr"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(12, "Jul"));
    lineSeries.DataPoints.Add(new CategoricalDataPoint(19, "Oct"));
    lineSeries.ShowLabels = true;
    this.radChartView1.Series.Add(lineSeries);

    LineSeries lineSeries2 = new LineSeries();
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(13, "Jan"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(15, "Apr"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(17, "Jul"));
    lineSeries2.DataPoints.Add(new CategoricalDataPoint(22, "Oct"));
    lineSeries2.ShowLabels = true;
    this.radChartView1.Series.Add(lineSeries2);

    ((CartesianArea)this.radChartView1.View.Area).ShowGrid = true;

    int i = 1;
    foreach (DataPointElement dpe in this.radChartView1.Series[0].Children)
    {
        dpe.IsVisible = false; AnimatedPropertySetting setting = new AnimatedPropertySetting();
        setting.StartValue = false;
        setting.EndValue = true;
        setting.Property = UIChartElement.IsVisibleProperty;
        setting.ApplyDelay = 40 + 40 * i;
        setting.NumFrames = 2;
        setting.ApplyValue(dpe); i++;
    }i = 1;
    foreach (DataPointElement dpe in this.radChartView1.Series[1].Children)
    {
        dpe.IsVisible = false; AnimatedPropertySetting setting = new AnimatedPropertySetting();
        setting.StartValue = false; setting.EndValue = true;
        setting.Property = UIChartElement.IsVisibleProperty;
        setting.ApplyDelay = 60 + 60 * i;
        setting.NumFrames = 2;
        setting.ApplyValue(dpe); i++;
    }
}

Workaround:
Perform the animation in the Shown event.

To reproduce:

public Form1()
{
    InitializeComponent();

    Random rand = new Random();
    for (int i = 0; i < 3; i++)
    {
        LineSeries lineSeries = new LineSeries();    
        lineSeries.DataPoints.Add(new CategoricalDataPoint(rand.Next(-50, 50), "Jan"));
        lineSeries.DataPoints.Add(new CategoricalDataPoint(rand.Next(-50, 50), "Apr"));
        lineSeries.DataPoints.Add(new CategoricalDataPoint(rand.Next(-50, 50), "Jul"));
        lineSeries.DataPoints.Add(new CategoricalDataPoint(rand.Next(-50, 50), "Oct"));
        this.radChartView1.Series.Add(lineSeries);
    }

    this.radChartView1.ShowLegend = true;
    this.radChartView1.ChartElement.LegendPosition = LegendPosition.Bottom;

    ((LineSeries)this.radChartView1.Series[0]).LegendTitle = "S&P 500";
    ((LineSeries)this.radChartView1.Series[1]).LegendTitle = "MSCI Emerging Markets TR Index";
    ((LineSeries)this.radChartView1.Series[2]).LegendTitle = "Great ETF";
}


Workaround:

Font f = new Font("Times New Roman", 10f, FontStyle.Regular);

private void Form1_Load(object sender, EventArgs e)
{
    foreach (LegendItemElement item in this.radChartView1.ChartElement.LegendElement.StackElement.Children)
    {
        item.Font = f;
    }
}

To reproduce:

public Form1()
{
    InitializeComponent();
    this.radChartView1.AreaType = ChartAreaType.Polar;
    Random rand = new Random();
    for (int i = 0; i < 80; i++)
    {
        RadarLineSeries s = new RadarLineSeries();
        s.ShowLabels = true;
        for (int j = 0; j < 8; j++)
        {
            s.DataPoints.Add(new CategoricalDataPoint(rand.Next(1, 100), "X" + j));
        }
       
        this.radChartView1.Series.Add(s);
    }
    this.radChartView1.ShowSmartLabels = true;
}

To reproduce:
LineSeries dailySeries = new LineSeries();
dailySeries.BorderColor = Color.DarkBlue;
dailySeries.BorderWidth = 1;
dailySeries.PointSize = new SizeF(5, 5);
dailySeries.ShowLabels = true;

for (int i = 0; i < 100; i++)
{
    dailySeries.DataPoints.Add(new CategoricalDataPoint(rnd.Next(100), DateTime.Now.AddMonths(i)) { Label = "old" });
}

DateTimeCategoricalAxis categoricalAxis = new DateTimeCategoricalAxis();
categoricalAxis.DateTimeComponent = DateTimeComponent.Date;

categoricalAxis.MajorTickInterval = 10;

categoricalAxis.PlotMode = AxisPlotMode.OnTicks;
categoricalAxis.LabelFormat = "{0:MMM-yy}";
categoricalAxis.ClipLabels = false;
categoricalAxis.LastLabelVisibility = AxisLastLabelVisibility.Visible;

CartesianArea area = this.radChart.GetArea<CartesianArea>();
area.ShowGrid = true;
CartesianGrid grid = area.GetGrid<CartesianGrid>();
grid.DrawHorizontalFills = true;
grid.BorderDashStyle = System.Drawing.Drawing2D.DashStyle.DashDot;

//First assign the axis to the VerticalAxis property and then add the series to the chart
dailySeries.HorizontalAxis = categoricalAxis;

this.radChart.Series.Add(dailySeries);

Workaround: 
Use different value for the MajorTickInterval.