I remembered that years ago I made a number of small lined bags with a flap. The lining was put in as one piece, with no topstitching on the edges. I could not remember how to do it. It is really easy to put in a lining on a bag without a flap, but I was having difficulty working out how to sew in the flap, without top-stitching the top edge. Anyway I got it. Notice the buttons are not sewn in place yet. There is a buttonhole under the the grey button. There is something about completing a project that I have problems with. Now all I have to work out is how to put a lining in, using the same method, on a bag with gussets!