eclipse-theia/theia

Preference change does not fire an onPreferencedChanged event

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#7685 opened on Apr 28, 2020

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bughelp wantedpreferences

Description

Bug Description:

While working on the new preferences-ui we came across a bug related to the preference-service that has been causing some strange and unpredictable behavior on the Electron version (and also appears on master with the original preferences UI). When setting a preference value for some items, most noticeably Application Confirm Exit in User scope, the preference service does not properly register an onPreferenceChanged event, and thus does not update the value in the UI. This has sometimes occurred for other preference items in folder scopes as well, but is consistently an issue for Application Confirm Exit Please see the attached screen recording with console output:

Steps to Reproduce:

  1. Set up a log for the preferenceService.onPreferenceChanged event (in e.g. packages/preferences/src/browser/preferences-decorator.ts around line 36)
  2. Build for Electron
  3. Run in Electron
  4. Open Preferences in User scope
  5. Modify preferences using tree view and save the JSON
  6. Every modify + save cycle should fire an onPreferenceChanged event.
  7. Modify 'Application: Confirm Exit' and save
  8. Observe that no event fires

screenrecord

Additional Information

  • Operating System: Linux (RHEL7 & Ubuntu tested)
  • Theia Version: Electron 1.0.0

Contributor guide

Tech stack
typescriptelectronnodejs
Domain
full stackdesktop
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScriptTheia frameworkEvent driven programming
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Start by examining the preference service event emission in packages/preferences/src/browser/preferences decorator.ts (around line 36). Investigate why the 'Application: Confirm Exit' preference in User scope does not trigger onPreferenceChanged. Check the implementation of preference service to see if the event is properly registered and if the change is detected. Review the issue comments for any additional context or hints.