There's a few different ways:

1 - window select from left to right to only capture the sphere that is inside the box, starting from outside the box. Make sure you start on the left side and move towards the right - this creates a window selection that only captures objects that are strictly inside the window, this type of window will show a box with a solid color outline. If you go from right towards the left for the window, it will capture anything that intersects the window at all - this type of window shows with a dashed outline.

2 - select the big box first and use hide, then select the sphere, then show the box.

3 - select the box and do an invert.


But this is the type of situation where a wireframe display mode would come in handy. I don't think that a wireframe mode will be available for V1 though, it's relatively complex to provide different display modes since it has a major effect on selection code.

- Michael