World._accel.GetUpdatedKeys() only returns properties for stimuli that are visible

Accelerated Shady.World instances can return all updated keys (canonical property names of the World and all stimuli that have changed value since last frame) with World._accel.GetUpdatedKeys(), but only visible stimuli are checked, which makes it impossible to use this method to access the initial values of a stimulus without first making it visible.

Also: is RecordUpdate() called on custom properties?