SeriesData has no elements after IWindowService property changed

Hi,

I’m creating a custom modifier that is derived from a VerticalSliceModifier. Basically if I press CTRL+Click, a VerticalLineAnnotation is added to the VerticalLines property, and tooltips with Y values are displayed. I’m using a collection of LineRenderableSeriesViewModel as data to chart. It works with one detail: my chart is within a tab, and when the tab changes and then returns, the tooltips disappear.

After further investigation, I noticed that the SeriesData ends up with 0 elements after the tab switch. To fix this, I have overrided the OnPropertyChanged on the class, and if the property that changed is “IWindowService”, I remove all markers if new value is null and add them back when new value is not null.

I don’t know why the “IWindowService” property is changed, or what the implications of that are. So even when the solution works, I don’t understand the internal mechanics of why it does.
I feel like there should be a better way to solve this. Can you help me out, or at least explain the internal workings?

I tried using the OnAttach and OnDetached events, but even when I remove the VerticalLines, somehow they keep appearing on the chart, and are not listed in the new VerticalLines collection.