there are some strange mouse interactions when placing in the 3d view after clicking the "cancel" or "accept" buttons. for example, the first time I create a list it works fine: one click to place each. However, if I stop, delete, and start adding again then it doesn't work the same way: the first click makes a fiducial, but subsequent clicks only occasionally place new fidus. I think the problem is that the interactor is selecting the new first fiducial even if the mouse is very far away - can click on the other side of the screen and drag that fiducial, even after pressing "stop" again.