Why do I get black bars when I insert my 16:9 clips and set as thumbnail?

If you insert 16:9 clips in PowerProducer and set as thumbnail, it will add black bars on the top and bottom because the thumbnail is designed as a 4:3 rectangle. If you want to change the 16:9 clips to 4:3, right-click on the clip and select Properties. Then select 4:3 and the black bars are removed, but the picture may be distorted.