alloc attrbuf
call draw chain
histogram attibutes
histogram background colors
erase window with most occuring background color (mobc)
for each line:
  sx=0;
  while sx<width
    ex=sx+1;
    while(ex attr.bg==sx attr.bg) ex++
    erase bg
end

for each line:
  sx=0
  while sx<width && sx<linedend
    ex=sx+1;
    while(ex attr.font==sx attr.font && ex attr.fg==sx attr.fg) ex++
      draw string with fg+font
end