gtk:tree-view-path-at-pos (view x y)

view -- a gtk:tree-view widget
x -- an integer for the x position to be identified (relative to the bin window)
y -- an integer for the y position to be identified (relative to the bin window)
path -- a gtk:tree-path instance, or nil
column -- a gtk:tree-view-column object, or nil
xcell -- an integer for the x coordinate relative to the cell
ycell -- an integer for the y coordinate relative to the cell

Finds the path at the point (x,y), relative to bin window coordinates. That is, x and y are relative to an events coordinates. Widget relative coordinates must be converted using the gtk:tree-view-convert-widget-to-bin-window-coords function. It is primarily for things like popup menus. If the path argument is non-nil, then it will be filled with the gtk:tree-path instance at that point. If the column argument is non-nil, then it will be filled with the column at that point. The xcell and ycell values return the coordinates relative to the cell background, for example, the background argument passed to the gtk:cell-renderer-snapshot function. This function is only meaningful if view is realized. Therefore this function will always return false if view is not realized or does not have a model.

For converting widget coordinates, for example, the ones you get from the "query-tooltip" signal, please see the gtk:tree-view-convert-widget-to-bin-window-coords function.