It looks like Cmd+Arrow key combination creates anchor, even though it should not (Mac Only).

Steps to reproduce:
1. run HelloTreeTableView app (Simple tab)
2. select Root node (this node becomes the anchor)
3. move focus to Child Node 2 by using Cmd+Down (should not change the anchor)
4. press Shift+Down arrow

Result: Child Node 2 and Child Node 3 are selected
Expected Result: All nodes in Simple tab are selected

Please note that this issue is most likely relevant to TreeView, TableView, and ListView too.