Hi, This is due to API changes in libmate-desktop 1.10. You just need to wait for mate-screensaver 1.10 to migrate to unstable and testing - it will be built fine against libmate-desktop 1.10.
- Bug#796452: mate-screensaver: FTBFS: error: too many arg... Chris West (Faux)
- Bug#796452: mate-screensaver: FTBFS: error: too man... Vlad Orlov

