iScreensaver : macOS 10.13 ScreenSaver changes, issues and bugs

Legacy document: iScreensaver 6 provides full support for macOS 10.13 and higher.
Please read about the latest version.

Background | iScreensaver in macOS 10.13 High Sierra | OS and Screensaver bugs in macOS 10.13

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Last Update: Thursday, 26-Mar-2020 00:23:30 PDT

Background & Summary

In macOS 10.13 (High Sierra) Apple has made a number of changes in several areas: Screensavers, Screen Saver Preferences, Password Protection, Energy Saver and the Lock Screen. This technical note helps document all of these issues, and will be updated as the situation changes.

The information here is of specific use to anyone using iScreensaver Designer software, but should also be of general use to those interested in writing, using, or managing Screen Savers or System Security / Lock Screen behavior on macOS 10.13.

Key Points

iScreensaver and macOS 10.13

Screensavers built with iScreensaver 5.1.1 or earlier will not function properly under macOS 10.13. Although many functions work normally (Installing, Previewing, Setting Preferences, and Uninstalling) when the actual screensaver runs normally, nothing is visible. The user will see only a blank screen. At the present time there is no known workaround for these issues on 10.13 when using screensavers built with iScreensaver 5.1.1 or earlier. Multiple bug reports have been submitted to Apple but we have not received any solutions or assurances of fixes at this time.

Interim Solution

iScreensaver Authors who wish to support 10.13 should upgrade to the latest version of iScreensaver Designer, re-build and re-issue their screensavers. This will fix the most serious issues:


iScreensaver Designer, the editing and authoring software, works on both Macintosh and Windows PC computers and either version will create screensavers for both platforms.

Version Released 17 May 2024 See Release Notes.

mac os x
Download iScreensaver Designer 6
for macOS 10.12 to 14

79.3 MB
Download iScreensaver Designer 6
for Windows 10 (64 bit) or Windows 11 (64 bit)

61.6 MB

iScreensaver 5.2 features that work in 10.13 High Sierra:

iScreensaver 5.2 features that do not work, or work differently, in 10.13 High Sierra:

Bugs, Issues, and Cautions about Screen Savers and Screensaver Security in macOS 10.13

Even if you are not using iScreensaver software, there are a number of issues related to screensavers, security and the lock screen, and other features in macOS 10.13. Some of these were discovered by us, and for some credit is due elsewhere. We hope this list is a helpful starting point for anyone using, managing, or programming screensavers under macOS 10.13.

Note: all issues below are found in the GM release of macOS 10.13 and are independent of and unrelated to iScreensaver software. These are due to bugs or changes made by Apple. The information here has not been provided by or verified by Apple, Inc. and should be used with caution.


Security, Preferences, and Lock Screen Behavior

Window Layer Changes

In 10.12 and earlier, the ScreenSaverEngine would display its content in window layer 2002. This meant that other applications could still display content and have it appear above the screensaver, if they needed to. In 10.13 this behavior has changed, and applications are no longer able to display content in front of the screensaver. It is not clear if this is an intentional change on Apple's part, or simply a bug. There is evidence that it may be a bug ( See above for the issues regarding bugs in ScreenSaverEngine when using the -background flag.) The implication is that any application which needs to alert the user of any information while a screensaver is running, is no longer able to do so. (Submitted as RDAR 34215758, 32665348).

Also note that there has been a longstanding SDK/Documentation bug: NSScreenSaverWindowLevel has always been defined as 1001, but the actual number seems to be 2002. See NSScreensaverWindowLevel and BOINC/macglutfix.m.

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Legacy Document: iScreensaver 6 provides full support for macOS 10.13 and higher.
Please Read about the latest version

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