I've fixed this bug in the attached patches. The first solves the problem with minimal changes, but is inefficient as it computes the entire (multi-monitor) wallpaper once per monitor rather than computing it just once, resulting in an added delay of a second or two with a large multimonitor setup. The second patch fixes that inefficiency, but touches a lot more of the code.
To apply this patch to your 16.04 system: mkdir work && cd work # get second.diff and put it here sudo apt build-dep unity apt source unity cd unity-7.4.0+16.04.20160906/ patch -i ../second.diff -p1 DEB_BUILD_OPTIONS="nocheck" dpkg-buildpackage -us -uc -nc -j10 sudo dpkg -i ../*.deb Henry/others: If you're feeling like a retroactive bounty, my Bitcoin address is on http://forre.st/ -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1291359 Title: multiscreen spanning wallpaper does not span on lock screen To manage notifications about this bug go to: https://bugs.launchpad.net/unity/+bug/1291359/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs