box_height = function(node)
  local y = 0
  for i=1,#node.editor.lines do
    local line = node.editor.lines[i]
    if node.editor.line_cache[i] == nil then
      node.editor.line_cache[i] = {}
    end
    node.editor.line_cache[i].fragments = nil
    node.editor.line_cache[i].screen_line_starting_pos = nil
    Text.compute_fragments(node.editor, i)
    Text.populate_screen_line_starting_pos(node.editor, i)
    y = y + scale(node.editor.line_height)*#node.editor.line_cache[i].screen_line_starting_pos
	print('height', i, node.editor.line_height, #node.editor.line_cache[i].screen_line_starting_pos, y)
    Text.clear_screen_line_cache(node.editor, i)
  end
  return y
end