API Review: Custom context menu Spellcheck

[anuragkumar878]

Spellcheck Suggestions for Custom Context Menus

Enables host apps rendering custom context menus to discover, retrieve, and apply spellcheck suggestions for misspelled words in editable fields. Introduces a
deferred capability discovery pattern on EventArgs2 that is extensible to future async capabilities without additional EventArgs versions.

New Interfaces:

ICoreWebView2ContextMenuRequestedEventArgs2 extends ICoreWebView2ContextMenuRequestedEventArgs

• get_DeferredCapabilities(flags*) — Returns a bitmask indicating which async capabilities are available for this context menu invocation (e.g., SPELL_CHECK).
• GetDeferredCapability(REFIID, void**) — IID-based accessor to acquire a capability interface. Returns E_NOINTERFACE if the capability is not applicable.

ICoreWebView2ContextMenuSpellCheck (acquired via GetDeferredCapability)

• get_MisspelledWord(LPWSTR*) — Returns the misspelled word under the cursor.
• GetSpellCheckSuggestionsAsync(handler) — Registers a one-shot completion handler that fires exactly once (always asynchronously) with spellcheck suggestions.
  Fires immediately (via PostTask) if suggestions are already resolved, or deferred until ready.

ICoreWebView2GetSpellCheckSuggestionsCompletedHandler

• Invoke(errorCode, suggestions) — Callback delivering an HRESULT and an ICoreWebView2ContextMenuItemCollection. Each item is a standard
  ICoreWebView2ContextMenuItem with Label (suggestion text) and CommandId (opaque identifier).

Usage flow:

1. Host receives ContextMenuRequested, QIs for EventArgs2
2. Checks DeferredCapabilities for SPELL_CHECK flag
3. Calls GetDeferredCapability(IID_SpellCheck) to acquire spellcheck interface
4. Sets Handled = TRUE, takes deferral
5. Reads MisspelledWord, calls GetSpellCheckSuggestionsAsync with handler
6. Handler fires with ICoreWebView2ContextMenuItemCollection → host builds menu
7. User selects → host sets args->put_SelectedCommandId(item->CommandId)
8. Completes deferral — runtime applies the correction via unified commanding

Key design decisions:

• Suggestions returned as ICoreWebView2ContextMenuItem objects (not strings) — consistent with existing menu item types
• Unified commanding via SelectedCommandId — same path as Cut, Copy, Paste; no separate ApplySpellCheckSuggestion method
• Suggestion item Name set to "spellCheckSuggestion" for machine-readable identification
• E_ILLEGAL_METHOD_CALL on double handler registration (no silent replacement)
• Direct QI for SpellCheck from EventArgs returns E_NOINTERFACE — forces EventArgs2 discovery path to distinguish "old runtime" from "not applicable"

[anuragkumar878]

@microsoft-github-policy-service agree company="Microsoft"

[Copilot]

Pull request overview

This PR introduces a new API review spec to extend the existing WebView2 ContextMenuRequested customization flow with spellcheck support, enabling hosts that render custom context menus to surface and apply spellcheck suggestions.

Changes:

• Adds a new spec describing custom-context-menu spellcheck scenarios and motivation.
• Provides Win32 C++ and C# example flows for querying suggestions, handling async readiness, and applying a suggestion.
• Proposes new Win32 COM interfaces (ICoreWebView2ContextMenuTarget2, ICoreWebView2ContextMenuRequestedEventArgs2) plus corresponding .NET/WinRT projections.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 4 comments.

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[shrinaths]

Review Summary

The architecture and design are sound — DeferredCapabilityDiscovery, ContextMenuItemCollection return type, unified SelectedCommandId commanding, and always-async callback are all well done. The comments below focus on bringing the spec up to the polish expected for Windows API review board submission:

Must fix:

• Placeholder UUIDs (lines 260, 298, 320) — generate real values
• .NET projection should use [interface_name] pattern, not EventArgs2 class (line 363)
• Verify MIDL3 format requirement with SDK team (line 233)

Should fix:

• Rename title to "Spellcheck Support for Custom Context Menus"
• Complete the samples (both C++ and C# have undefined helpers / placeholder comments)
• Add CHECK_FAILURE() consistently in C++ sample
• Fix SelectedCommandId default value in error table (it's -1, not 0)

Nit:

• Consistent casing of "spellcheck" in prose
• Avoid contractions per Microsoft style guide
• Use /// doc comments in .NET projection
• Clean up casual language ("for example -")