I chose cycles render as the render engine, went into the world panel, clicked in the surface part onto use nodes and selected from color environment texture.
Now when I am in the rendered mode of viewport shading, I can see the texture environment and it lights my glossy cube as it should be, but when I scroll the mouse-wheel, the size of the cube changes and the size of the environment texture stays the same.
How can I achieve to move with a camera inside this environment texture and zoom into parts of it?