Fix vertical candidate window flickering

[lukhnos]

The flickering issue is more often found with the vertical candidate window, likely due to the layout passes it needs to go through. This PR makes sure that candidate window position is first set before the window becomes visible.

This PR also switches to use dispatch queue for all delayed method invocation. This makes sure that all such deferred actions are put in the same queue, and so they will be performed in the expected order.

[gemini-code-assist]

Summary of Changes

Hello @lukhnos, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the user experience by eliminating an annoying flickering artifact in the vertical candidate window. The core changes involve reordering the sequence of operations to guarantee that the window's layout is finalized before it's displayed. Additionally, it refactors the mechanism for scheduling delayed UI tasks to use DispatchQueue, which improves the reliability and consistency of these operations across the application.

Highlights

• Flickering Fix: Addresses and resolves a flickering issue specifically observed with the vertical candidate window.
• Window Visibility Timing: Ensures that the candidate window's position is fully determined and set before the window is made visible, preventing it from appearing at an incorrect initial location.
• Standardized Delayed Actions: Migrates all delayed method invocations to use DispatchQueue.main.asyncAfter, ensuring a consistent and predictable order of execution for deferred UI updates.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request addresses a flickering issue with the candidate window by ensuring the window's position is set before it becomes visible. This is achieved by reordering operations in InputMethodController.swift. Additionally, it standardizes on using DispatchQueue for delayed operations in CandidateController.swift, which is a good move for consistency.

My review includes a couple of suggestions to simplify the DispatchQueue calls for better code clarity. Overall, the changes look good and address the stated problem.

[Copilot]

Pull Request Overview

This PR fixes flickering issues with the vertical candidate window by ensuring the window position is set before making it visible. The changes also standardize delayed method invocation to use DispatchQueue.main.asyncAfter for consistent execution order.

• Move visibility setting to occur after position calculation in InputMethodController.swift
• Replace NSObject.perform(_:with:afterDelay:) with DispatchQueue.main.asyncAfter in CandidateController.swift

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
Source/InputMethodController.swift	Moves visible = true to execute after window position is set via set(windowTopLeftPoint:bottomOutOfScreenAdjustmentHeight:)
Packages/CandidateUI/Sources/CandidateUI/CandidateController.swift	Replaces perform(_:with:afterDelay:) with DispatchQueue.main.asyncAfter for ordering window visibility operations