This python plug-in was part of Python archive found at Werner Hartnagel's sourceforge site located at:
I had to define a second pattern layer (pat_lay2 - "Scanlines2") in order to keep the plugin from throwing an error when the mask option is set to NO. The error indicated that the layer had already been added to the image, so it appears gimp_edit_clear wasn't clearing the pat_lay from memory, just from the image. To offset the error, the newly pat_lay2 substitutes for pat_lay and adds a transparent empty layer named scanlines2 to the top of the layer dialog. Using the mask option works without errors.
I got this plugin working with Vista 64, Vista 32, XP on GIMP 2.6.7