After calling this function, any newly initialized gizmos will be given the provided reference transform as their custom reference transform. This mainly meant to allow the UI to be used in a 2D situation (e.g. UV editor) where the gizmos only have two axes. Normally, we only allow delta mode in such a case, but the 2D editor can provide the used plane's reference transform to allow the gizmos to be usable in destination mode as well.