why cant i get my size box to be the size i tell it?

I have a widget that is contained in a size box, no matter what I set the height/width overrides to be I get the exact same result

yet when I run it the size box is tiny and its contents spill out everywhere.

that tiny blue box is the border set to fill the size box, and should be surrounding everything else. so why wont my size box resize? I can tell it to be 50 or 5000000 pixels wide and nothing changes at all. am I misunderstanding the purpose of a size box? am I missing some hard to find setting somewhere? or is this just broken?

do you use the anchor function?