render frame buffer postion poblem, i would like to fix postion

macroScript showrender category:"cho render"

my_vfb = bitmap 1 1

render rendertype: #blowup outputSize:[300, 212] to:my_vfb


i made this script
but there is problem
i render screen , i move frame buffer postion in other space postion
and i render again , frame buffer postion is same first postion
so i have to move again

can i fix render frame postion ?