In ClarisDraw 1.0, placing a clone on an upper layer, selecting an object from a lower layer, then Undoing "Use Library" results in both the clone and selected object disappearing.
To reproduce:
1. Launch ClarisDraw.
2. Draw an object on Layer 1.
3. Create a New Layer.
4. Open any library, then drag a clone from it on Layer 2.
5. Option-click on the object from Layer 1 to select it.
6. Undo Use Library.
Notice that both clone and the selected object have disappeared. Choosing "Redo Use Library" brings both back.