How to: Dock an Annotation to a Pane
To anchor an annotation to the required pane, specify the PaneAnchorPoint.Pane property. Then, define the axes and their values to specify the anchor point using the PaneAnchorPoint.AxisXCoordinate and PaneAnchorPoint.AxisYCoordinate properties.
Note
A complete sample project is available at https://github.com/DevExpress-Examples/how-to-customize-chart-annotations-t376991.
<dxc:Annotation.AnchorPoint>
<dxc:PaneAnchorPoint Pane="{Binding ElementName=defaultPane}">
<dxc:PaneAnchorPoint.AxisXCoordinate>
<dxc:AxisXCoordinate Axis="{Binding ElementName=xAxis}"
AxisValue="2.85"/>
</dxc:PaneAnchorPoint.AxisXCoordinate>
<dxc:PaneAnchorPoint.AxisYCoordinate>
<dxc:AxisYCoordinate Axis="{Binding ElementName=yAxis}"
AxisValue="-30"/>
</dxc:PaneAnchorPoint.AxisYCoordinate>
</dxc:PaneAnchorPoint>
</dxc:Annotation.AnchorPoint>