Create a full frame size square.

• Tools -> Roto -> Full square

• A Roto node with a full frame size square is created.

• Copy 'fullSquare' folder in your .Natron folder.
• Add following lines to your 'initGui.py' file, where <path> is the location of 'fullSquare' folder.

from <path>.fullSquare.fullSquare import *
NatronGui.natron.addMenuCommand('Tools/Roto/Full square','fullSquare()')