How to get Mesh Element Index

how do i get the index of an mesh element i from the onClicked event ??
i get from touched component only the size of all elements (of the mesh) or the material of an spesific index but not the index of the element i clicked on…
i dont need the exact material on the mesh element when i know the index i can get it somewhere else…

I second this, got a similar problem when trying to determinate the clicked Bone from a Skeletal Mesh.