Below are the uses Of Relativesource That I Know Of In Wpf:

– Getting An Ancestor’S Property:

{Binding Path=Pathtoproperty,
Relativesource={Relativesource Ancestortype={X:Type Typeofancestor}}}
– Binding To Another Property On The Object:

{Binding Path=Pathtoproperty, Relativesource={Relativesource Self}}
– Bind To A Property On The Templated Parent:

{Binding Path=Pathtoproperty, Relativesource={Relativesource Templatedparent}}
Or
{Templatebinding Path=Pathtoproperty}

Original link

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https://www.c-sharpcorner.com/UploadFile/yougerthen/relativesources-in-wpf/