var bottom_left = g.toDomCoords(highlight_start, -20);
var top_right = g.toDomCoords(highlight_end, +20);
var left = bottom_left[0];
var right = top_right[0];
var bottom_left = g.toDomCoords(highlight_start, -20);
var top_right = g.toDomCoords(highlight_end, +20);
var left = bottom_left[0];
var right = top_right[0];