color_grid=220,220,220
grange=$[floor(2*$grid/$unit)]
step=$[$unit*$size/(4*$grid)]
grid_src=
!for i=-$grange to $grange
 !if $i!=0
  grid_src=$grid_src\
	line $border,$[$size/2+$border-rint($i*$step)],$[$border+$size],$[$size/2+$border-rint($i*$step)],$color_grid\
	line $[$size/2+$border-rint($i*$step)],$border,$[$size/2+$border-rint($i*$step)],$[$border+$size],$color_grid
 !endif
!next i
