There is no such button per se but if you create one big movie for the whole DVD and then split it into chapters, the play button will simulate 'play all'. You can spread the chapter menus over several submenus.
If you are looking for a button that will play every slideshow, etc on the disc one after the other, then no.
But if you have room, could you not create one 'mega-movie' slideshow with everything in it as a seperate item? Movies can be embedded within slideshows and I think there is no longer a limitation on length.