GtkTreeViewColumnFunc to use for the column. This
function is used instead of the standard attributes mapping for
setting the column value, and should set the value of tree.column's
cell renderer as appropriate. func may be NULL to remove an
older one.gtkTreeViewColumnSetCellDataFunc(object, cell.renderer, func, func.data = NULL)objectcell.rendererfuncGtkTreeViewColumnFunc to use.func.datafunc.