let set ?child_width ?child_height ?child_ipadx
?child_ipady ?layout w =
if child_width <> None || child_height <> None then
set_child_size w ?width:child_width ?height:child_height ();
if child_ipadx <> None || child_ipady <> None then
set_child_ipadding w ?x:child_ipadx ?y:child_ipady ();
may layout ~f:(set P.layout_style w)