I'd love the option to see what lies outside the bounds of my document and have those items be selectable. As an interactive designer I'm constantly shifting UI elements around during the design phase. It's often that I reposition or draw items where parts of them extend beyond the canvas and if I need to resize or rearrange these items it's difficult for me to see where they stop/start or exist if they lay outside the canvas. I don't see this as an "always on" option, but rather a toggle when I need it (much like hiding and showing guides) and where the items could even be faded back to 50% opacity, for example. I believe this would dramatically improve workflow efficiency.