r_margin_left;
	const dh = slider_h - slider_margin_top - slider_margin_bottom;

	ctx.fillRect(slider_margin_left, slider_margin_top, dw, dh);
	const lb01 = (lb - min_x) / (max_x - min_x);
	const ub01 = (ub - min_x) / (max_x - min_x);
	ctx.strokeStyle="#000000";
	ctx.fillStyle="#777777";
	ctx.fillRect(slider_margin_left + dw * lb01 - 0.5, slider_margin_top, dw * (ub01 - lb01) + 0.5, dh);

	ctx.font = "16px sans-serif";
	ctx.fillStyle="#d64562";
	// the whole interval
	ctx.textBaseline = "top";
	ctx.textAlig