Identify the panedwindow component underneath the point given by x and y, in window coordinates. If the point is over a sash or a sash handle, the result is a two-element tuple containing the index of the sash or handle and a word indicating whether it is over a sash or a handle, such as (0, 'sash') or (2, 'handle'). If the point is over any other part of the panedwindow, the result is an empty string.