fix: null dereference in get_SelectionContainer when no selection container exists

[Copilot]

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Why

get_SelectionContainer (UIA SelectionItemPattern.SelectionContainer) crashes with a null dereference when the element has no ancestor with a selection container. GetSelectionContainer() walks the parent tree looking for a view with multiselectable and required props set; if none is found it returns nullptr, which was immediately dereferenced on the next line.

What

• Added a null check on the return value of GetSelectionContainer() in get_SelectionContainer
• Returns S_OK with *pRetVal == nullptr when no container is found — correct per UIA spec (element is simply not inside a selection container)

auto selectionContainerView = GetSelectionContainer();
// Per UIA spec, returning S_OK with *pRetVal == nullptr is correct when the element
// is not contained within a selection container.
if (!selectionContainerView)
  return S_OK;

Screenshots

N/A

Testing

Reproduced by calling get_SelectionContainer on a selection item whose ancestor tree contains no multiselectable container. Verified the null check prevents the crash and returns S_OK with a null provider pointer.

Changelog

Should this change be included in the release notes: yes

Fix crash (null dereference) in UIA SelectionItemPattern.get_SelectionContainer when the element has no selection container ancestor.

Microsoft Reviewers: Open in CodeFlow