The problem I see with this is that the `TREXMainController` now knows how `_category` holds on to its test cases. In other words, you _assume_ that _copyTestCase will now be at the very end of the test case array.

A cleaner way would be to ask the _category for the index of the object. For now this will be an O(N) operation but there are ways to speed it up... and realistically, we won't encounter any performance problems with this.