Created attachment 161975 [details]
Video Example

SUMMARY
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System Settings ignoring failsafe timeout if window is closed before time expires.
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STEPS TO REPRODUCE
1. Open display settings.
2. Adjust a setting that uses a timeout failsafe to revert changes if the applied changes break the system and the user is unable to interact with settings window within the timeout period.
3. Close the display settings window before the timeout period expires.

OBSERVED RESULT
When the window is closed, the changes appear to be permanently saved.

EXPECTED RESULT
The changes should be reverted, as the user did not approve the applied changes during the failsafe timeout period. If the window is accidentally closed, crashes, the desktop environment restarts, or the system is shut down; then it should revert to the last known-good settings, instead of potentially trapping the user in a misconfigured or unusable system.

SOFTWARE/OS VERSIONS
Windows: n/a
macOS: n/a
Linux/KDE Plasma: Fedora 38
(available in About System)
KDE Plasma Version: 5.27.8
KDE Frameworks Version: 5.109.0
Qt Version: 5.15.10

ADDITIONAL INFORMATION
Note that the video example shows a different issue with OBS recording the cursor position incorrectly after the resolution change. It is unrelated to this bug report. However, it can be used to show the resolution was changed and did not revert after the window closed.