the F4 list would be clearer if each element copied from it to the target segment was simultaneously deleted from the list. If subsequently deleted from the target segment it should appear on the F4 list again. That would lessen the possibility of mistakes. It would be even better if the list in the same manner took into account copying non-translatables via ALT+I or copy and paste.
If you transfer non-translatables only via F4-list, you should notice that the transferred non-translatable is put at the end of the list. This way, the next non-translatable to transfer is always the first one on the list.