gtk:tree-list-row-depth (object)

object -- a gtk:tree-list-row object
depth -- an unsigned integer for the depth of the row

The accessor for the depth slot returns the depth in the tree of the row. Rows that correspond to items in the root model have a depth of zero, rows corresponding to items of models of direct children of the root model have a depth of 1 and so on. The depth of a row never changes until the row is removed from its model at which point it will forever return 0.