How to use "Stretch to Display" on version 1.4.2?

[LunaMoo]

@AbnormallyNormal nothing was removed, if you weren't updating for a long time - new screen was added called "Display layout editor"(under graphics settings) which includes all options related to fitting display to the screen, including stretching.

Stretching messes up pixel proportions and as far as I remember never was enabled by default so there's really nothing weird with having black bars, it just means your display doesn't match PSP resolution. Many people actually hate stretching since it morphs the image and introduces artifacts and blur.