No, in the suggestion thread I posted that idea, to have two columns in landscape mode for epubs etc., to simulate an open paper book - you see two pages at once there too, after all. That was my idea to fix the "wide text" problem on a 9.7" screen, something
parkher was refering to extensively earlier in this thread, since that would be somewhat like having two 6" screens very close together. Never thought of adding margins, seemed counterintuitive to buy a big screen only to reduce used area.
But Booxtor reports that now both approaches are possible, whatever fits one's needs - which is awesome!