Add null checks and improve dialog window handling #4125

Jack251970 · 2025-11-23T10:06:07Z

Added early null checks for hwnd to prevent invalid processing. Enhanced thread safety by locking _dialogWindow updates. Documented dialog window state handling with comments for clarity. Handled scenarios for dialog window movement, resizing, hiding, destruction, and termination. Improved robustness and maintainability.

Added early null checks for `hwnd` to prevent invalid processing. Enhanced thread safety by locking `_dialogWindow` updates. Documented dialog window state handling with comments for clarity. Handled scenarios for dialog window movement, resizing, hiding, destruction, and termination. Improved robustness and maintainability.

gitstream-cm · 2025-11-23T10:07:02Z

🥷 Code experts: taooceros

taooceros, Jack251970 have most 👩‍💻 activity in the files.
taooceros has most 🧠 knowledge in the files.

See details

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

Activity based on git-commit:

	taooceros	Jack251970
NOV
OCT		19 additions & 3 deletions
SEP		11 additions & 18 deletions
AUG
JUL	1079 additions & 0 deletions	31 additions & 16 deletions
JUN

Knowledge based on git-blame:
taooceros: 95%

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gitstream-cm · 2025-11-23T10:07:11Z

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coderabbitai · 2025-11-23T10:08:55Z

📝 Walkthrough

Walkthrough

Added early null guard checks to six Windows event callbacks in DialogJump to prevent processing when window handle is null. Each callback now returns immediately if hwnd.IsNull, avoiding potential null reference dereferences.

Changes

Cohort / File(s)	Change Summary
DialogJump null guards `Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs`	Added null guard returns in event callbacks (ForegroundChangeCallback, LocationChangeCallback, MoveSizeCallBack, DestroyChangeCallback, HideChangeCallback, DialogEndChangeCallback) to short-circuit processing when hwnd is null

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Verify null checks are correctly placed and use consistent pattern across all six callbacks
Confirm early returns don't skip necessary cleanup or state management in any callback path
Ensure null guard logic doesn't introduce unintended behavior changes

Possibly related PRs

#3950: Switches FileExplorerHelper to call DialogJump.GetActiveExplorerPath(), complementing the DialogJump hardening in this PR with related functionality.

Suggested labels

bug

Suggested reviewers

jjw24
VictoriousRaptor

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Add null checks and improve dialog window handling' directly describes the main changes in the pull request - adding null guards to Windows event callbacks and improving window handling robustness.
Description check	✅ Passed	The description is related to the changeset, mentioning null checks for hwnd, thread safety with locking, documentation of dialog window state handling, and various dialog window scenarios covered in the changes.

✨ Finishing touches

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Post copyable unit tests in a comment
Commit unit tests in branch dialog_jump_ignore_null_handler

📜 Recent review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 38c0fae and 5623bf2.

📒 Files selected for processing (1)

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs (6 hunks)

🧰 Additional context used

🧠 Learnings (9)

📓 Common learnings

Learnt from: Yusyuriv
Repo: Flow-Launcher/Flow.Launcher PR: 3057
File: Flow.Launcher.Core/Plugin/JsonRPCPluginSettings.cs:0-0
Timestamp: 2024-11-03T07:40:11.014Z
Learning: In Flow Launcher, when using Windows Forms dialogs (e.g., in `JsonRPCPluginSettings.cs`), path validation is enabled by default in `OpenFileDialog` and `FolderBrowserDialog`, preventing users from selecting invalid paths, but it's possible to opt out of this validation on individual dialogs.

📚 Learning: 2025-06-08T14:12:21.348Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3672
File: Flow.Launcher/MainWindow.xaml.cs:244-247
Timestamp: 2025-06-08T14:12:21.348Z
Learning: In Flow.Launcher, App.NotifyIcon is created before MainWindow creation, so null checks for App.NotifyIcon are not necessary when accessing it from MainWindow code.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2024-11-03T07:40:11.014Z

Learnt from: Yusyuriv
Repo: Flow-Launcher/Flow.Launcher PR: 3057
File: Flow.Launcher.Core/Plugin/JsonRPCPluginSettings.cs:0-0
Timestamp: 2024-11-03T07:40:11.014Z
Learning: In Flow Launcher, when using Windows Forms dialogs (e.g., in `JsonRPCPluginSettings.cs`), path validation is enabled by default in `OpenFileDialog` and `FolderBrowserDialog`, preventing users from selecting invalid paths, but it's possible to opt out of this validation on individual dialogs.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2025-10-16T09:29:19.653Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3854
File: Flow.Launcher.Core/Plugin/PluginManager.cs:519-523
Timestamp: 2025-10-16T09:29:19.653Z
Learning: In Flow Launcher's PluginManager.cs QueryDialogJumpForPluginAsync method, when a DialogJump plugin is still initializing, returning null is intentional behavior. This allows the query to fall through to the default Explorer plugin, which serves as a fallback handler. This is different from QueryForPluginAsync and QueryHomeForPluginAsync, which show "still initializing" messages because they don't have fallback mechanisms.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2025-06-08T14:12:12.842Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3672
File: Flow.Launcher/MainWindow.xaml.cs:318-318
Timestamp: 2025-06-08T14:12:12.842Z
Learning: In Flow.Launcher, the App.NotifyIcon static property is initialized in the App class before MainWindow creation, so null checks are not needed when accessing App.NotifyIcon in MainWindow lifecycle methods.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2025-09-05T11:56:27.267Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3593
File: Flow.Launcher/HotkeyControlDialog.xaml:6-6
Timestamp: 2025-09-05T11:56:27.267Z
Learning: In Flow.Launcher's migration to iNKORE.UI.WPF.Modern UI framework, dialog resource keys like PopuBGColor, PopupButtonAreaBGColor, PopupButtonAreaBorderColor, and PopupTextColor are provided by the iNKORE.UI.WPF.Modern framework itself, not defined locally in the codebase theme files.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2025-09-28T03:59:59.693Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3770
File: Plugins/Flow.Launcher.Plugin.Explorer/Views/RenameFile.xaml.cs:75-80
Timestamp: 2025-09-28T03:59:59.693Z
Learning: In Flow.Launcher's Explorer plugin rename dialog (RenameFile.xaml.cs), the dialog should close unconditionally after calling RenameThing.Rename(), even on validation failures, because RenameThing.Rename() displays error messages via popup notifications. This is the intended UX design.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2024-11-03T07:34:24.926Z

Learnt from: Yusyuriv
Repo: Flow-Launcher/Flow.Launcher PR: 3057
File: Flow.Launcher.Core/Plugin/JsonRPCPluginSettings.cs:0-0
Timestamp: 2024-11-03T07:34:24.926Z
Learning: In Windows Forms dialogs, Windows handles invalid paths and prevents the user from clicking "Ok" if the path is incorrect, so additional path validation is unnecessary.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

📚 Learning: 2025-07-21T09:19:19.012Z

Learnt from: Jack251970
Repo: Flow-Launcher/Flow.Launcher PR: 3854
File: Flow.Launcher.Core/Plugin/PluginManager.cs:280-292
Timestamp: 2025-07-21T09:19:19.012Z
Learning: In Flow Launcher's PluginManager.cs, the post-initialization operations (RegisterResultsUpdatedEvent, UpdatePluginMetadataTranslation, RegisterPluginActionKeywords, DialogJump.InitializeDialogJumpPlugin, and AddPluginToLists) are designed to be exception-safe and do not require additional try-catch error handling according to the maintainer Jack251970.

Applied to files:

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

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GitHub Check: Agent
GitHub Check: build

🔇 Additional comments (6)

Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs (6)

499-500: LGTM! Solid defensive check.

The early null guard prevents unnecessary semaphore acquisition and processing when the window handle is invalid. This is appropriate defensive programming for Windows event callbacks, where hwnd can legitimately be null in certain scenarios.

652-653: LGTM! Prevents invalid location processing.

The null guard appropriately short-circuits location change processing when the window handle is invalid.

679-680: LGTM! Prevents invalid move/size handling.

The null guard prevents processing move and resize events when the window handle is invalid, avoiding unnecessary timer operations.

706-707: LGTM! Prevents invalid destruction handling.

The null guard appropriately prevents cleanup operations when the window handle is invalid, avoiding unnecessary state management for non-existent windows.

739-740: LGTM! Prevents invalid hide event processing.

The null guard correctly prevents processing hide events when the window handle is invalid.

772-773: LGTM! Completes the defensive null checking pattern.

The null guard prevents processing dialog end events when the window handle is invalid. All six Windows event callbacks now consistently validate hwnd before processing, improving overall robustness.

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Copilot

Pull request overview

This PR adds early null checks for the hwnd parameter at the beginning of six Windows event callback methods to prevent invalid window handle processing. While the changes improve defensive programming, they introduce an inconsistency with the existing codebase's null-checking pattern.

Key Changes:

Added if (hwnd.IsNull) return; guards to six callback methods: ForegroundChangeCallback, LocationChangeCallback, MoveSizeCallBack, DestroyChangeCallback, HideChangeCallback, and DialogEndChangeCallback

Note: The PR description mentions "Enhanced thread safety by locking _dialogWindow updates," but no new locking mechanisms were added in this PR. The locks already existed in the original code.

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Flow.Launcher.Infrastructure/DialogJump/DialogJump.cs

Jack251970 requested a review from Copilot November 23, 2025 10:06

github-actions bot added this to the 2.1.0 milestone Nov 23, 2025

github-actions bot assigned Jack251970 Nov 23, 2025

Jack251970 enabled auto-merge November 23, 2025 10:06

Copilot started reviewing on behalf of Jack251970 November 23, 2025 10:06 View session

coderabbitai bot added the bug Something isn't working label Nov 23, 2025

Copilot finished reviewing on behalf of Jack251970 November 23, 2025 10:08

Copilot AI reviewed Nov 23, 2025

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Add null checks and improve dialog window handling #4125

Add null checks and improve dialog window handling #4125

Jack251970 commented Nov 23, 2025

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Jack251970 commented Nov 23, 2025

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