How to make interactable custom shape buttons

Is it real to create round button with round affection zone in new Unity UI system (or any other non square shape)? Masks do not work… They make button visually round but affection zone is still square… The button script is not editable and I cant look inside code…

Maybe you can add the RaycastMask component to the button image. You can get it at here: Unity UI Extensions

(Also, you need to set the button image to Read/Write Enabled in the texture settings.)