To create this look, I cut out a piece of black lace (sold by the yard at fabric stores) that was the same size as our screen. Using a thin needle and black thread, I made small stitches at each corner to tack the lace to the screen. The great part about this is that it only takes a few snips of a scissor to release it when I am tired of it.
Make a cornflour podge (aabout 2 tablespoons cornflour mixed with about an equal amount of cold water. Add to about a cup and a half of boiling water from the kettle. Use the resulting jelly to paint a thick layer onto the window pane. Cut out a rectangle of ironed lace using a template. Paste onto the pane, and cover with another layer of podge. Leave to dry. Wash with warm water to remove.