function get_icon_for_tools(tools) {
	if (tools.length === 1) {
		return get_icon_for_tool(tools[0]);
	}
	const icon_canvas = make_canvas(16, 16);

	Promise.all(tools.map((tool) => load_image_simple(`help/${tool.help_icon}`)))
		.then((icons) => {
			icons.forEach((icon, i) => {
				const w = icon_canvas.width / icons.length;
				const x = i * w;
				const h = icon_canvas.height;
				const y = 0;
				icon_canvas.ctx.drawImage(icon, x, y, w, h, x, y, w, h);
			});
		});
	return icon_canvas;
}
@param {Tool[]} tools  an array of selected tools
@returns {HTMLImageElement | HTMLCanvasElement}  an icon representing the tools