fix: prevent app list item overlap after drag on Wayland

[yixinshark]

Summary

• Use an invisible dummy item as the drag target in the categorized app list.
• Keep the visible ItemDelegate under ListView layout control during Wayland drag operations.
• Preserve dock drag-and-drop MIME data for pinning apps to Dock.

Test plan

• Built successfully with cmake --build /tmp/dde-launchpad-build.
• Verified on Wayland/Treeland that dragging items in sort-by-name and sort-by-category modes no longer leaves list items overlapped after release.

Pms: BUG-295171

Summary by Sourcery

Bug Fixes:

• Resolve item overlap in the categorized app list after drag-and-drop on Wayland by using a separate dummy drag target instead of the visible item delegate.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Adjusts the Wayland drag behavior in the windowed app list so that drag operations use an invisible dummy item as the drag target, preserving the layout of the visible ItemDelegate and preventing item overlap after drag.

Sequence diagram for Wayland drag using dummy Item target

sequenceDiagram
    actor User
    participant MouseArea
    participant dndTarget
    participant ItemDelegate
    participant WaylandCompositor

    User->>MouseArea: pressAndHold
    MouseArea->>MouseArea: startDrag
    MouseArea->>dndTarget: set drag.target
    MouseArea->>WaylandCompositor: initiateDrag(dndTarget)
    Note over ItemDelegate,WaylandCompositor: ItemDelegate remains under ListView layout control
    User->>MouseArea: release
    WaylandCompositor-->>MouseArea: drop
    MouseArea->>ItemDelegate: updateModelOrder
    Note over ItemDelegate: No visual overlap after drag on Wayland

Loading

File-Level Changes

Change	Details	Files
Use an invisible dummy Item as the drag target instead of the ItemDelegate to keep ListView layout intact during Wayland drag operations.	Add a dummy Item inside the MouseArea to serve as the drag.target during drag-and-drop Update the MouseArea drag.target binding from the ItemDelegate to the new dummy Item Keep existing drag enablement logic that disables dragging while category menus are open	qml/windowed/AppListView.qml

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it. You can also reply to a
  review comment with @sourcery-ai issue to create an issue from it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time. You can also comment
  @sourcery-ai title on the pull request to (re-)generate the title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time exactly where you
  want it. You can also comment @sourcery-ai summary on the pull request to
  (re-)generate the summary at any time.
• Generate reviewer's guide: Comment @sourcery-ai guide on the pull
  request to (re-)generate the reviewer's guide at any time.
• Resolve all Sourcery comments: Comment @sourcery-ai resolve on the
  pull request to resolve all Sourcery comments. Useful if you've already
  addressed all the comments and don't want to see them anymore.
• Dismiss all Sourcery reviews: Comment @sourcery-ai dismiss on the pull
  request to dismiss all existing Sourcery reviews. Especially useful if you
  want to start fresh with a new review - don't forget to comment
  @sourcery-ai review to trigger a new review!

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[deepin-ci-robot]

deepin pr auto review

★ 总体评分：100分

■ 【总体评价】

代码通过引入虚拟拖拽目标完美解决了Wayland环境下的布局破坏问题，质量极高
逻辑正确、注释清晰且无任何安全风险，无需扣分

■ 【详细分析】

• 1.语法逻辑（完全正确）✓

在 AppListView.qml 的 MouseArea 组件中，新增了一个空 Item 作为 drag.target，成功将拖拽行为与实际的 itemDelegate 视图解耦。此方式有效规避了 Wayland 协议下 DnD 操作直接移动原组件导致的布局错乱，逻辑严密且符合 QML 语法规范。
建议：保持当前的实现方式，无需额外修改

• 2.代码质量（良好）✓

代码新增了详细的英文注释，准确解释了使用 dummy Item 的原因，极大提升了可读性和可维护性。变量命名 dndTarget 符合驼峰命名规范且语义明确，代码结构简洁。
建议：在 UOS 系统的组件中，建议将注释统一为中文以保持代码库风格一致

• 3.代码性能（高效）✓

新增的 Item 是一个没有任何子对象、无绑定属性、无渲染内容的轻量级空节点，其在 Qt Scenegraph 中的内存占用和渲染开销几乎为零，对整体列表滑动和交互性能无任何负面影响。
建议：保持现状，无需优化

• 4.代码安全（存在0个安全漏洞）✓

漏洞对比统计：新增漏洞 0 个，减少漏洞 0 个，持平 0 个
本次代码修改仅涉及 QML 前端 UI 视图的拖拽目标重定向，完全隔离于后端业务逻辑、文件系统、网络通信及命令执行环境，不存在任何攻击面。

• 建议：继续保持这种纯视图层修改的安全隔离意识

■ 【改进建议代码示例】

                MouseArea {
                    id: mouseArea
                    anchors.fill: parent

                    // 使用虚拟 Item 作为 drag.target，防止 Wayland 拖拽破坏原始 ItemDelegate 布局
                    Item { id: dndTarget }
                    
                    acceptedButtons: Qt.LeftButton | Qt.RightButton
                    drag.target: dndTarget
                    // 当分类菜单打开时，禁用拖拽功能
                    enabled: !(ddeCategoryMenu.visible || alphabetCategoryPopup.visible)

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: robertkill, yixinshark

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• debian/deepin/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment