https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.hittestfiltercallback?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-9.0
HitTestFilterCallback Delegate (System.Windows.Media) | Microsoft Learn
Represents the callback method that specifies parts of the visual tree to omit from hit test processing.
windows mediadelegatesystemmicrosoftlearn