Perhaps Wim can add an option to turn off the screensaver and/or detect it running and disable the webcam or similar.
I don't think that is the answer. The screen saver keeps running, as usual, even though DSS_RMT has told it to stop. When that happens, WebLook doesn't have a problem, even though the screen saver starts and stops as it normally does. It just stops screen saving with other programs, until the program stops running. There is some sort of interference between Weblook, and Doodle's Screen Saver.
It doesn't make sense to always disable the webcam, just because screen saving has started, although that may be a good option. A user who wants to monitor a sleeping baby doesn't really need (or want) to have the screen active, but the camera needs to keep working.
This afternoon, I disabled DSS all together, and Weblook has not, yet, misbehaved (about 5 hours).
Mozilla uses this to do housekeeping when the screensaver is running on the basis that if the screensaver is running then the user isn't doing anything.
This is probably a bad assumption, but I can't think of a better way to do it. At least the user is less likely to notice that Mozilla is using machine cycles.