In OFIW, when typing Ctrl+Arrow or Ctrl+Space I expect the selection in the list control to get updated. As it is now, hand-picked multi-selections must be made with the mouse :(
I disagree. What you see is a bug due to the fact that Shift+Tab needs to be pressed.
Edit control has focus. 1) You press Up/Down. The selection is changed in the list control (this must be explicitly implemented). 2) You press Ctrl+Space or Ctrl+Up/Down. Nothing happens (not implemented).
Hence, you get different behavior. Either remove 1) or add 2).
You are asking for Space to select or unselect items in the list, while you are sitting in an edit control. Normally space adds a space character in the edit control, which is very useful when using multiple filters at once. To me that sounds quite inconsistent.