A grid.layout object is used to
generate the margins. A second viewport selecting the
mid-row/col is used to create the effect of margins
prPushMarginViewport(bottom, left, top, right, name = "margin")2 - the number of pushed viewports
The margin object, either in npc or a unit object,
or a vector of 4 if you want the same margins allover.
The margin object, either in npc or a unit object.
The margin object, either in npc or a unit object
The margin object, either in npc or a unit object
The name of the last viewport