Provide a way to invoke the tooltip for a concrete data point programmatically

Labels in bar series are cut, when setting the labels VerticalAligment to Top:

The data points should allow setting shape and color to each one individually.

On WinUI: Two PieSeries are displayed. 

On Android: Crash occurs

On iOS: negative value is displayed in chart

Hi

I have the following chart

      <telerik:RadPieChart Grid.Row="1">
        <telerik:RadPieChart.Series>
          <telerik:DonutSeries ItemsSource="{Binding CurrencyAllocation}" x:Name="CurrSeries"
                               LabelBinding="Item1"
                               ValueBinding="Item2"
                               ShowLabels="True"
                               AllowSelect="True"
                               SelectedPointOffset="0.1"/>
        </telerik:RadPieChart.Series>
        <telerik:RadPieChart.ChartBehaviors>
          <telerik:ChartSelectionBehavior DataPointSelectionMode="Single"
                                          SeriesSelectionMode="None"
                                          SelectionChanged="Chart_SelectionChanged" />
        </telerik:RadPieChart.ChartBehaviors>
      </telerik:RadPieChart>

As soon as I set the SelectedDataPointOffset to a lowish value, no matter whether it's 0.5, 0.1, 0.01, 0.001 or even 0.0000001, the offset when selecting the data point is always the same and it's so large that it's unusable, as you can see in the following screenshot.

As an additional issue, if i set the offset to 0.9, i get an exception

'RelativeOffsetFromCenter is not valid! The possible values are in the [0, 1] interval.'

as soon as I select a segment. 0.9 obviously is in the [0, 1] interval.

Improve performance when adding many series and data points are constantly added and increased
For example chart slows the performance when 4th series with many data points are added. 

For the test, I have used ScatterLine series.

The VisibleRange property can hold the actual visible minimum and maximum of the axis while the chart is being zoomed and panned.

Let's say I set the number of labels to 4 on that axis (see attached pic).  It would then be up to the axis to auto generate the labels depending on the data and zoom.  There would always be four labels shown on the axis regardless of zoom so the user could always have context regardless of the zoom.  The labels would just change to reflect what is currently being viewed at the current zoom level.