Thank you for replying! I'm sorry to bother you with this - I may just be too inexperienced to solve this. I followed the tutorial you linked, but I'm unsure what you mean with 'the effect should be drawn by PPFX itself". After adding FX_Sketch to the xternal effects like the tutorial described I did this:
// CREATE EVENT
var effects = [
new FX_Sketch(true),
];
main_profile = new PPFX_Profile("Main", effects);
ppfx_id.ProfileLoad(main_profile);
// POST DRAW EVENT
ppfx_id.DrawInFullscreen(application_surface);
Is this wrong?