and this script is useful to change Layer of selected lines
import pcbnew
board = pcbnew.GetBoard()
Dwgs_User=40
for drw in board.GetDrawings():
if drw.IsSelected():
drw.SetLayer(Dwgs_User)
where Layers nbrs are:
(0 F.Cu signal)
(31 B.Cu signal)
(32 B.Adhes user)
(33 F.Adhes user)
(34 B.Paste user)
(35 F.Paste user)
(36 B.SilkS user)
(37 F.SilkS user)
(38 B.Mask user)
(39 F.Mask user)
(40 Dwgs.User user)
(41 Cmts.User user)
(42 Eco1.User user hide)
(43 Eco2.User user)
(44 Edge.Cuts user)
(45 Margin user hide)
(46 B.CrtYd user)
(47 F.CrtYd user)
(48 B.Fab user)
(49 F.Fab user)