8f79fa9c67 was an attempt to fix this already, but it didn't quite
work. Problem was that the tooltip was messing with the drop-box and
operator properties, setting the name property for its own internal
logic. This name property would then be used rather than the session
UUID to query the material, which gave the wrong material (linking can
result in multiple IDs of the same type with the same name). A followup
commit will further sanitize this.