bkh, nice job on the pin-stripe script. I'd suggest, however, that you use 'gimp-context-set-paint-method' so that your script is ensured to paint with the pencil or paintbrush, regardless the active paint tool. As currently written, depending upon what paint tool is active when the script is executed, the result might not be as expected.
Since the PDB browser does not list the available methods, I will post them here: "gimp-pencil", "gimp-paintbrush", "gimp-eraser", "gimp-airbrush", "gimp-ink", "gimp-clone", "gimp-heal", "gimp-perspective-clone", "gimp-convolve", "gimp-smudge", and "gimp-dodge-burn". The values are indeed strings, so the quotation marks should be included in the procedure call. For example,
(gimp-context-set-paint-method "gimp-paintbrush")