Version 4.0.27 adds a new capability to the LSW – you can change the order of layers.
Originally the order that layers were drawn in was in the order that they were defined in the techfile – or the order they are encountered in GDS/OASIS/LEF etc.
Now you can change this ordering. Left clicking and dragging a layer in the LSW allows to to drop the layer above another layer.
Saving a techfile or saving a library now saves the layers in the current order.