smart stretch
 

I like using bs player. When I have a 4:3 movie to view I use Power DVD because it has a smart stretch feature which turns the 4:3 signal into a 16:9 output. I wish BS player had this feature

You can do that using Shift + 1, +2 and +3 (original, 16:9, 4:3)

I believe that smart stretch is different than any of the aspect ratios that you mentioned. I am aware that one can shift through the various aspect ratios.

Smart stretch though is a function that takes a 4:3 movie and turns it into a 16:9 without distorting the image. Going from 4:3 to 16:9 flattens everything out

Then you have to throw away information from the top and/or bottom of the picture (so called "Pan & Scan").

That will be a smart cut, not a smart stretch. :)