 reset_scale_over ? button_high_color : button_color;
			context.fillText("[reset scale]", buttons_x + reset_scale_down, reset_scale_y + reset_scale_down);
			context.fillStyle = snap_to_f_over ? button_high_color : button_color;
			context.fillText("[ snap to f ]", buttons_x + snap_to_f_down, snap_to_f_y + snap_to_f_down);
		}
	}

	function snap_focus_to_nearest() {
		// translation
		const functions = s2x_x2s_s2y_y2s();
		const s2x = functions[0];
		const x2s = functions[1];
		const s2y = functions[2];
		