how to make idvd slideshow fill widescreen display

Hi,

I made a slideshow in iPhoto, then exported it to iDVD, where it automatically made a new iDVD project. I switched the project to 16:9 widescreen since the people I am sending this to have a widescreen TV. The menu is widescreen, but the slideshow previews with gray bars on each side of the window, as if it's still in standard. Does anyone know how it's possible to make the slideshow so that it would fill an entire widescreen display?

Thanks