Describe the bug
When a collapsed TreeViewItem (that has a parent TreeViewItem) has the focus and the left arrow key is pressed nothing happens:

Expected behavior
When a collapsed TreeViewItem (that has a parent TreeViewItem) has the focus and the left arrow key is pressed the focus moves to the parent:

Describe the bug

When a collapsed TreeViewItem (that has a parent TreeViewItem) has the focus and the left arrow key is pressed nothing happens:
Expected behavior

When a collapsed TreeViewItem (that has a parent TreeViewItem) has the focus and the left arrow key is pressed the focus moves to the parent: