Provide downscaled background style

Submitted by José Luis González

Assigned to Eric Koegel

Link to original bug (#13227)

Description

There's a scaled background style that scales images to screen size respecting the images proportions. However this option stretches images to occupy all of the screen when they are smaller. This is undesirable in most cases since upscaled images look ugly due to interpolation (well, really, that there were not that many pixels in the original image).

It would be useful if a downscaled style was added that only scaled images when they were bigger than the screen but doesn't upscale them if they are smaller. IMHO this should be the default behaviour of scaled, the other being stretch, but if scaled isn't going to change I think a downscaled is necessary. Please raise severity if this is considered a bug in scaled.

Version: 4.12.3