It Would be nice to have a mode in gallery where you could tell that the menu using a galley is meant for wallpapers.
Automatic detection of screen for users that want to download a wallpaper with the size of their screen and when its saved it actually saves it at that size or a button to set it as wallpaper.
Dont know how this could be done.. but here is the request
moslty the wallpapers sites use standard download button (direct link) or the window with full image like here: