I tired to create a polygon cube in accordance with one of the tutorials I'm following. What I wanted was something similar to this:

(Random picture from google.)
However what I ended with creating was only the outline of the cube, while the faces of each side remained transparent. This makes it rather hard to see what lines belongs to the cube and what are part of the underlining mesh in the background. Here is how it appears at my computer:

(Screen capture taken by me.)
I have tried to look through the various menus to see if there is anything to check to make it appears like desired, but I haven't found anything. I guess there is something really obvious I'm missing ... Still, I need help to find it.
