Accessibility: Tooltips do not appear when using keyboard navigation

[BenBeckley]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version:
• OS Version:

We received this issue from accessbility testing of our VS Code extension. It is also reproducible using vscode-extension-samples/tree-view-sample. The issue is essentially that treeitem tooltips are not being shown when using keyboard navigation.

Steps to Reproduce:

1. Run the tree-view-sample
2. Open a workspace that contains node packages in the Explorer
3. Open the Package Explorer side bar and refresh
4. Now the treeview should be populated
5. Use keyboard navigation (Tab, arrow keys) to navigate through the treeview elements

Expected: The tooltips should appear while using keyboard navigation. Actual: The tooltips do not appear on keyboard navigation, but do appear on mouse hover.