Issue #3290 is a NullReferenceException in GetNodeByVisibleIndex that is
provably unreachable single-threaded: TreeFlattener.Count and
GetNodeByVisibleIndex read the same totalListLength fields back to back, so a
stale index yields ArgumentOutOfRangeException, never an NRE. A stress harness
with reader threads racing an IsExpanded/Children mutator reproduces exactly
that NRE, so the crash requires a mutation from a foreign thread. The rule that
a displayed tree is only mutated from the UI thread was pure convention:
ICSharpCode.ILSpyX/TreeView contained no VerifyAccess, lock or dispatcher of any
kind, and two tree nodes already carry a Dispatcher.UIThread.Invoke workaround
for the same hazard, which means it has been hit before and fixed one site at a
time.
ICSharpCode.ILSpyX is host-agnostic and must not name a dispatcher, so ownership
is stated by the host instead of inferred: SetOwner(Thread) marks the thread
allowed to mutate a node and its subtree. Unowned means unchecked, which is what
makes the analyzer pattern legal - build a subtree on a worker, publish it on
the UI thread - without an exception carved into the rule.
The owner is resolved by walking up the model-parent chain to the nearest
explicit owner rather than stamped onto every node. That buys the propagation
rules for free: one call on the root covers the whole displayed tree, children
attached later inherit it with no bookkeeping, and a subtree built off-thread is
unchecked while it is being built yet inherits the owner the moment it is
attached - an attachment which is itself a checked mutation of the owned tree.
A subtree that already carries a different owner would otherwise leave one
displayed tree demanding two threads, so that case is reported once and the
incoming owner dropped, rather than reported on every later mutation. Re-owning
is allowed because handing a tree over is the point, but the handoff must come
from the current owner: a background thread taking a live tree away from the UI
is the race being hunted.
The check sits in SharpTreeNodeCollection.OnCollectionChanged, which every
Children mutator funnels through, and in the IsExpanded and IsHidden setters -
the three entry points that invalidate totalListLength. Checking in
OnCollectionChanged also means a violation is reported before OnChildrenChanged
rewrites the flat-list tree, so the AVL structure is left intact.
Violations are collected rather than fatal by default, with per-call-site
deduplication and a count, and the first hit of each site written straight
through to a log file so a long exploratory session can be read while it runs.
FailFast makes them throw so tests can observe one deterministically.
Everything is behind #if DEBUG plus [Conditional("DEBUG")], so the release build
has no field on SharpTreeNode and no call at any site; verified by decompiling
the release assembly.
Assisted-by: Claude:claude-opus-5:Claude Code
Backfills the standard MIT X11 header on hand-written files that never
got one, attributing each to its first-commit author and year from git
history. Code vendored from dotnet/runtime and Humanizr/Humanizer gets
its origin's license lines and a provenance note instead. Generated
files (Resources.Designer.cs, the version-info template), tool-managed
suppression files, and BAML test-case fixtures intentionally stay
header-less.
Assisted-by: Claude:claude-fable-5:Claude Code
The UseNestedNamespaceNodes and HideEmptyMetadataTables handlers both
force a materialised node to re-create its children (clear, re-arm
LazyLoading, EnsureLazyChildren), guarded on it not already being lazy.
That's a general tree-node operation -- a soft, in-place rebuild that
re-runs LoadChildren without reloading the assembly -- so it belongs on
SharpTreeNode next to the lazy contract it builds on, not as a private
helper in the model. Both call sites now use node.ReloadChildren().
Assisted-by: Claude:claude-opus-4-8:Claude Code
NodesInserted/NodesRemoved reported a multi-node change (a node plus its visible
descendants -- a contiguous run) as a sequence of single-item Add/Remove events,
but the underlying tree updates Count by the WHOLE run before they fire. A
consumer that reconciles the change one item at a time and re-indexes the source
mid-sequence then reads against a Count that has already dropped by the full run:
Avalonia's SelectionModel does exactly this (it re-reads SelectedItems while
handling each Remove), indexing past the end and throwing ArgumentOutOfRangeException
out of TreeFlattener's indexer whenever a selection was live during a bulk reshape
(e.g. toggling UseNestedNamespaceNodes). It only surfaced under full-suite timing,
which is why it read as flaky.
Raise one ranged event for the whole run instead, so the notification matches the
tree's state in a single step and Count/indices stay in agreement. The indexer
keeps throwing on genuine out-of-range access. Avalonia 12.4's virtualization and
selection handle ranged Add/Remove (every expand/collapse exercises it); full
headless suite is green.
* Changes necessary for making SharpTreeNode cross platform by proxying System.Windows dependencies
* Add ITreeNodeImagesProvider for node icons
* Move InternalsVisibleTo to csproj (possible since net50)
* Move view models and other xplat class for SharpTreeView to ILSpyX, Windows-dependent classes to ILSpy/Controls/TreeView
* Move GetDoubleClickTime to NativeMethods
Siegfried Pammer
Lex Li
Jan Kučera
Peter Crabtree
tom-englert
Christoph Wille