You've mentioned the DFX style so I assumed when you mentioned the separation of categories I am assuming you are referring to this. That said, the DFX style has separate categories. Now you've mentioned the default style, I'm assuming you mean the xenforo default style? Which style are you referring to? the xenforo default or DFX which actually has category separation?
Don't worry about your english, we will get there.
He mentioned the XF default style and the fact that in the DXF style, the categories are hooked together like in the default style.
He is wanted each category and it's forums to be separated into their own block, just like each block on the sidebar is separate.