High Sierra: Wallpaper mode not working

[Waitsnake]

I saw on YT a video that shows that the wallpaper mode is not working in High Sierra.

Since I'm still on El Capitan I can't analyze the problem at the moment.

Possible reasons:

1. I found this forum where the discuss that the LaunchAgent in High Sierra only allows some narrow privileges of the agent file. But I'm not sure if this is really a problem since AnimatedGif don't give any strange file privileges. Anyway it needs to be checked.
   See:
   https://www.apfeltalk.de/community/threads/problem-mit-launchd.521676/

2. I read that the directory of the screensaver engine has moved! This is definitely a problem of AnimatedGif since the path is used in the launchd script that AnimatedGif creates.
   macOS 10.12 and earlier: /System/Library/Frameworks/ScreenSaver.framework/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine
   macOS 10.13: /System/Library/CoreServices/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine
   See:
   https://iscreensaver.com/help/notes/high_sierra/high_sierra.shtml

3. The command-line parameters to ScreenSaverEngine are broken in 10.13 (Submitted as RDAR 34481351). AnimatedGif can not fix the ScreenSaverEngine.
   See:
   https://iscreensaver.com/help/notes/high_sierra/high_sierra.shtml
   https://www.reddit.com/r/techsupport/comments/7h1526/background_command_broken_macos_highsierra_10131/

[Waitsnake]

After installing High Sierra on one of my systems I start to experiment on this issues.

If I change the path as described in 2. in the launchd-script and restart the script manually with launchctl the screensaver starts with AnimatedGif. Since I not change any privileges as described in 1. before it proves that 1. is not an reason of the problem, but 2. is a problem.

Unfortunately the screensaver is than drawn in foreground and not in Background as wallpaper. This confirms the issue of 3. witch is a bug in the screensaver engine. Tryout 2. is kind of dangerous experiment since you install a launchd-script witch activates automatic after log-in and starts the screensaver in absolute foreground (bug 3.) and than you see not any window or any other element (!). Only the screensaver is visible! Fortunately the GUI still reacts to mouse and keyboard and I had still a terminal open and could blindly type-in the command to stop the launchd-script. So take care what you are doing.

[Waitsnake]

I analyses the problem further and doing a lot of different tests.

The conclusion is that in Systems before 10.13 the background-mode of ScreenSaverEngine creates an normal window in background but for normal screensaver-mode it uses a own space that is in front of desktop space. Since 10.13 it creates also for the background-mode this own space in front of the desktop space and so the desktop is not longer visible in background-mode.

Fortunately the ScreenSaverEngine also has a window-mode that still works in 10.13 and simply open the screensaver in a normal window on the desktop. The code change the windows properties of this normal-window to look like an background-window.

I add the workaround for issues 2. and 3. with last commit.

[Waitsnake]

The new release 1.3.4 is out an issue can be closed.