The generic function
over-pinboard-object-p returns non-nil if the
coordinates specify a point within the boundary of a pinboard object. To find the actual object at this position, use pinboard-object-at-position.
The default method returns
are within the bounding area of the pinboard object. A method is supplied for line-pinboard-object and you may add methods for your own pinboard-object subclasses.
CAPI User Guide and Reference Manual (Unix version) - 25 Feb 2015