LT-22452 - fix mouse scrolling on date field in lex edit

[johnml1135]

JIRA Explanation for LT-22452

Problem:
Mouse wheel scrolling does not work in the Lexicon Editor when the cursor is over the Date field (and potentially other non-ButtonLauncher controls in the DataTree).

Root Cause:
The Date field (DateSlice in BasicTypeSlices.cs) wraps a RichTextBox set to ReadOnly with BorderStyle.None. RichTextBox inherits from ScrollableControl and has internal scroll machinery that consumes WM_MOUSEWHEEL messages without propagating them to the parent DataTree. Win32 delivers WM_MOUSEWHEEL to the focused window handle (the RichTextBox), so the message never reaches DataTree and its AutoScrollPosition property is never updated — the pane doesn't scroll.

This is a general WinForms problem: any child control that internally handles WM_MOUSEWHEEL (e.g. RichTextBox, ListView, TreeView) will swallow the mouse wheel and prevent its container from scrolling.

Fix:
Added a WheelRedirector inner class to DataTree that implements IMessageFilter — a .NET/WinForms mechanism that intercepts Windows messages at the application message pump before they are dispatched to any window. This is the same pattern used in 7 other places in the FieldWorks codebase (e.g. FwFindReplaceDlg, SimpleRootSite, FwApp).

When WM_MOUSEWHEEL is intercepted, the filter checks whether the cursor is over any live DataTree instance. If so, it calculates the new scroll position using the same AutoScrollPosition/AutoScrollMinSize API that DataTree itself uses, applies it, and marks the message as handled. This ensures consistent scrolling regardless of which child control has focus.

Changes:

• DataTree.cs: Added WheelRedirector inner class (~65 lines), Register() call in constructor, Unregister() call in Dispose.
• DataTreeScrollTests.cs: New test verifying the scroll position calculation works correctly.
• No changes to ButtonLauncher.cs or any other file.

Made changes.

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This change is 

[github-actions]

NUnit Tests

    1 files      1 suites   5m 42s ⏱️
4 411 tests 4 324 ✅ 87 💤 0 ❌
4 420 runs  4 333 ✅ 87 💤 0 ❌

Results for commit 7ac2ac0.

♻️ This comment has been updated with latest results.

[jasonleenaylor]

It looks like this test adds another test that pops up a window while it is running. I was hoping to get away from that, I'd rather not have a unit test for this if that is the case.

@jasonleenaylor reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: 1 of 3 files reviewed, all discussions resolved.

[Copilot]

Pull request overview

Adds an application-level IMessageFilter to ensure DataTree scrolls when the mouse wheel is used over child controls that consume WM_MOUSEWHEEL (e.g., RichTextBox inside DateSlice), and introduces configuration stubs in Serena project settings.

Changes:

• Register/unregister a static WheelRedirector to intercept WM_MOUSEWHEEL and update DataTree.AutoScrollPosition.
• Add WheelRedirector inner class implementing IMessageFilter to redirect wheel scrolling based on cursor location.
• Extend .serena/project.yml with additional (currently unset) configuration keys.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
Src/Common/Controls/DetailControls/DataTree.cs	Installs a message filter to redirect mouse-wheel scrolling to DataTree regardless of focused child control.
.serena/project.yml	Adds new Serena configuration keys for line endings and read-only memory patterns.

Comments suppressed due to low confidence (1)

Src/Common/Controls/DetailControls/DataTree.cs:1

• Unregister() is called unconditionally, including when disposing == false (finalizer path). Since Application.Add/RemoveMessageFilter is thread-affine (per-UI-thread message loop), attempting to remove the filter from a non-UI/finalizer thread may not actually remove it (leaking the filter/list entry) and can introduce cross-thread issues. Move the s_wheelRedirector.Unregister(this); call inside the if (disposing) block (or otherwise ensure it executes on the same UI thread that performed Register).

// Copyright (c) 2015-2017 SIL International

[johnml1135]

@jasonleenaylor - I removed the test. It doesn't really need a test, I was just trying to replicate it. It's hard to replicate without a full test. That is another PR (getting true no-popup testing).