macOS High Sierra hides windows on the "assistive tech" window level when on lock screen

Number:rdar://37207524 Date Originated:04-Feb.-2018 11:39 AM
Status:Open Resolved:
Product:macOS + SDK Product Version:10.13.2
Classification:Serious Bug Reproducible:Always
Apps used to be able to present their own UI on top of the lock screen by using the cursor (kCGCursorWindowLevelKey ) or assistive tech (kCGAssistiveTechHighWindowLevelKey) window levels to f.ex. provide means of virtual input.

In macOS High Sierra 10.13.2, these windows only display while the user is logged in - but no longer appear on the lock screen.

Steps to Reproduce:
1) Open window with windowLevel kCGCursorWindowLevelKey or kCGAssistiveTechHighWindowLevelKey
2) Select "Lock Screen" from the Apple menu.

Expected Results:
The window is still shown on the lock screen.

Actual Results:
The window is not shown on the lock screen.


A word on 

- if there's another way to display app UI on the lock screen and
- whether this change was intentional

would be highly appreciated. Thanks in advance!


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