`KeyBinding.owner` trait is problematic

The `KeyBinding.owner` trait is set when a new `KeyBindings` object is created from a list of `KeyBinding` instances. However, when editing a `Keybindings` a new, temporary `KeyBindings` object is created with the sorted, flattened list of `KeyBinding` objects, and the `owner` assigned to this temporary object (which is then kept around as long as the `KeyBinding` instances exist or until the next time it is edited).

The `owner` trait is used for ascertaining that there are no other `KeyBinding` in the current set which conflict with changes, and to reset the potentially matching changes if the user OKs it. It is also used to check whether the current `KeyBindingEditor` has focus, which is currently held on the `KeyBindings` object that is actively being edited.