The part of annotaion that exceed the aixs are not displayed

[yangchao320]

Steps to reproduce

1.open the plot
2.add an arrow annotation that the startpoint and endpoint are both on the X-aixs

Platform:
.NET version: dotnet6
oxyplot version: 2.1.0

Expected behaviour

show the full view of the arrow annotation

Actual behaviour

the half bottom of the arrow annotation that exceed the axis is not visible

[sunwayking]

This is because of that annotations rendering layer is below title, box and normally axes.

[VisualMelon]

Annotations always ask to be clipped to the plot area: you can disable this by overriding the GetClippingRect method on the annotation and returning OxyRect.Everything. An alternative presentation option would be to add some padding or margins to the axes so that the 0 line are not on the very edge of the plot