Fix for ListBox ghost items

[timunie]

What does the pull request do?

Fixes an issue where a ListBox with 0 width can produce ghost items. See #15194 for a repro.

What is the current behavior?

A ListBox of size 0 can produce ghost items.

What is the updated/expected behavior with this PR?

No more ghost items.

How was the solution implemented (if it's not obvious)?

Ensure that those items are recycled.

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

Fixes #15194

[Copilot]

🟡 Changes recommended

ScrollIntoView can now return a container instance that it has just recycled/removed, which can hand callers a control that is no longer in the panel’s visual tree.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR addresses a virtualization edge case where ListBox/VirtualizingStackPanel can leave behind visible “ghost” item containers when scrolling while the control effectively has no usable width (e.g., hidden pane scenarios), and adds a regression test covering the reported repro from #15194.

Changes:

• Recycles the temporary _scrollToElement when it fails to be adopted into the realized range, preventing it from remaining as a visible, unindexed internal child.
• Adds a new unit test that simulates scrolling selection changes while the ListBox has Width = 0, then expanding it, asserting no visible unrealized containers appear.

File summaries

File	Description
src/Avalonia.Controls/VirtualizingStackPanel.cs	Recycles an unadopted scroll-to container to prevent ghost elements after pane expansion.
tests/Avalonia.Controls.UnitTests/ListBoxVirtualizationIssueTests.cs	Adds regression coverage for zero-width scrolling + expand scenario to ensure no ghost containers remain visible.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[avaloniaui-bot]

You can test this PR using the following package version. 12.2.999-cibuild0069503-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[avaloniaui-bot]

You can test this PR using the following package version. 12.2.999-cibuild0069522-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]