function SubGraph(canvas, name, color)
{
	if (canvas === undefined)
	{
		canvas = document.createElement("canvas");
		canvas.style.position = "absolute";
	}

	this.canvas = canvas;
	this.name = name !== undefined ? name : "default";
	this.color = color !== undefined ? color : DOMUtils.getCSSVariable("--color-light");
	this.values = [];
	this.buttons = [];
	this.onchange = null;
}
Graph lines represents a subgraph in the graph GUI object.

@constructor
@class SubGraph
@param {Element} canvas Drawing canvas.
@param {string} name Name of the graph used to acces its data.
@param {string} color Color of this subgraph.