gtk:widget-compute-point (widget target point out)

widget -- a gtk:widget object to query
target -- a gtk:widget object to transform into
point -- a graphene:point-t instance for a point in the coordinate sytem of widget
out -- a graphene:point-t instance for the corresponding coordinates in the coordinate system of target

The graphene:point-t instance if the point could be determined, nil on failure, in this case, out is set to (0,0).

Translates the given point in the coordinates of widget to coordinates relative to the coordinate system of target. In order to perform this operation, both widgets must share a common root.