vimScrollByB :: (Int -> Int) -> Int -> BufferM ()
vimScrollByB f n = do h <- askWindow actualLines
                      vimScrollB $ n * f h

-- | Move to middle line in screen
vimScrollByB :: (Int -> Int) -> Int -> BufferM ()
vimScrollByB f n = do h <- askWindow actualLines
                      vimScrollB $ n * f h

-- | Move to middle line in screen
vimScrollByB f n = do h <- askWindow actualLines
                      vimScrollB $ n * f h

-- | Move to middle line in screen