[slate] How to get widget for which OnMouseButtonDown was called?

[anonymous_user_2f7014b11 (anonymous_user_2f7014b1)]

I have OnMouseButtonDown handler for SBorder widget. How to get widget that was clicked inside of OnMouseButtonDown handler?

FReply FDamageAreaCustomization::OnMatrixCellClick(const FGeometry& Geometry, const FPointerEvent& Event)
{
    SBorder* clickedWidget = ???
}