I notice one can not use fullscreen gallery for site background (globally) I do not see that as an option from Spaceship Appearance. I also notice the bg image is treated differently in Spaceship Appearance then if one upload in post or page. the latter will stretch nicely and cover full screen re how the screen resize.
Comments
About body background image - yes it is left with natural behaviour, no stretching, cause it is for other purpose(you can even repeat background to put some pattern there). When we will add global album, we will also add global single photo that will be stretched.
Thanks for pointing this one:-)
With regards.