Refactor index tuples to structs

[SOF3]

No description provided.

[anhosh]

Thank you, I really like this changeset, it cleans up a lot of code and adds some quite useful iterators. I only have a few comments which I've posted.

[SOF3]

I am removing the Into conversions from *Path to *Index since that would create confusing APIs such as

let third_tab = NodePath::new(NodeIndex(2), TabIndex(3));
tree.set_active_tab(third_tab, TabIndex(4))

which reads really weird since we are'nt actually setting the active tab to third_path.

[anhosh]

Very nice. I'll merge this once the last two small comments have been addressed.

[SOF3]

Fixed. This would be a breaking change btw, so a separate version bump would be required before tagging.

[Copilot]

Pull request overview

This PR refactors the docking API to replace (SurfaceIndex, NodeIndex, TabIndex) tuple addressing with explicit NodePath / TabPath structs, and introduces fallible accessors (Result/Error) for safer node/tab operations.

Changes:

• Introduce NodePath and TabPath types and migrate tab/node movement/removal/drag-and-drop code to use them.
• Add dock_state::Error/Result and make “set active tab” operations fallible instead of silently ignoring invalid indices.
• Update public TabViewer hooks and examples to use NodePath.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/widgets/tab_viewer.rs	Update TabViewer callbacks (context_menu, on_add, add_popup) to accept NodePath.
src/widgets/dock_area/tab_removal.rs	Refactor removal queue entries to store NodePath / TabPath.
src/widgets/dock_area/state.rs	Import order cleanup.
src/widgets/dock_area/show/mod.rs	Update docking UI logic to use NodePath/TabPath for removals, detach, and DnD sources.
src/widgets/dock_area/show/leaf.rs	Convert leaf rendering, context menus, detach/close paths, and focus tracking to NodePath/TabPath.
src/widgets/dock_area/mod.rs	Update internal DockArea state (to_detach, new_focused) to store path structs.
src/widgets/dock_area/drag_and_drop.rs	Refactor DnD TreeComponent and destination mapping to path structs.
src/utils.rs	Import ordering change.
src/dock_state/tree/tab_index.rs	Add TabPath and related helpers/conversions.
src/dock_state/tree/node_index.rs	Add NodePath and helpers (MAIN_ROOT, left_node, right_node).
src/dock_state/tree/node/mod.rs	Add indexed tab iterators (iter_tabs_indexed, iter_tabs_mut_indexed).
src/dock_state/tree/node/leaf.rs	Make LeafNode::set_active_tab return Result with Error::InvalidTab.
src/dock_state/tree/mod.rs	Re-export new path types; update TabDestination::Node to carry NodePath; add safe leaf/leaf_mut; make Tree::set_active_tab fallible.
src/dock_state/surface.rs	Add indexed node iterators and return tab indices from iter_all_tabs(_mut).
src/dock_state/mod.rs	Add Error/Result; add safe accessors (node, node_mut, leaf, leaf_mut); refactor move/detach/remove APIs to NodePath/TabPath; make DockState::set_active_tab fallible.
src/dock_state/error.rs	New error type used by fallible dock/tree operations.
examples/text_editor.rs	Handle fallible set_active_tab via expect.
examples/tab_add_popup.rs	Update example tab metadata and TabViewer hook signatures to use NodePath.
examples/tab_add.rs	Update add-button plumbing to use NodePath.
examples/simple.rs	Minor formatting/import cleanup.
examples/save_load_dock_state.rs	Import order cleanup.
examples/reject_windows.rs	Minor formatting/import cleanup.
examples/hello.rs	Update context_menu signature to accept NodePath.
Cargo.toml	Add thiserror dependency for the new error type.

[SOF3]

copilot comments also resolved