i think this is what you are after, but i'm not sure
do you mean 100% of your design size, so if it is 17" wide you only see the ~13.5" that fits on your laptop screen?
edit: the more i ponder your wording, the more i think this is what you mean
but i will leave the rest up in case it helps someone else down the road
if you look along the top toolbar there is a little square icon that looks like it has a small cross in it
this will give you a 'full ratio/scaled' view of your page size (not design, page size)
so if you have a 12"x12" page size then it will center that, if you have 12"x140" it will ratio that to your screen
here's a pic to show the button