Highcharts Treemap Drilldown/drillup issue - highcharts

Question

I am trying to capture drill up/down event when using HighCharts treemap as in example http://jsfiddle.net/ghh1x7vt/1/
I will have to dynamically set the data label size/color as i drill down/up. Can someone help me doing this?
$(function () {
var data = {
"Eastern Mediterranean": {
"Egypt": {
"Communicable & other Group I": "74.3",
"Noncommunicable diseases": "781.7",
"Injuries": "33.5"
},
"South Sudan": {
"Injuries": "143.4",
"Communicable & other Group I": "831.3",
"Noncommunicable diseases": "623.4"
},
"Sudan": {
"Injuries": "133.6",
"Noncommunicable diseases": "551.0",
"Communicable & other Group I": "495.0"
},
"Libya": {
"Injuries": "62.8",
"Noncommunicable diseases": "550.0",
"Communicable & other Group I": "52.6"
},
"Jordan": {
"Noncommunicable diseases": "640.3",
"Injuries": "53.5",
"Communicable & other Group I": "52.5"
},
"Pakistan": {
"Communicable & other Group I": "296.0",
"Noncommunicable diseases": "669.3",
"Injuries": "98.7"
},
"Djibouti": {
"Noncommunicable diseases": "631.1",
"Communicable & other Group I": "626.0",
"Injuries": "106.0"
},
"Syrian Arab Republic": {
"Communicable & other Group I": "41.0",
"Injuries": "308.0",
"Noncommunicable diseases": "572.7"
},
"Morocco": {
"Noncommunicable diseases": "707.7",
"Communicable & other Group I": "131.5",
"Injuries": "47.0"
},
"Yemen": {
"Communicable & other Group I": "515.0",
"Noncommunicable diseases": "626.9",
"Injuries": "84.3"
},
"Bahrain": {
"Injuries": "33.5",
"Noncommunicable diseases": "505.7",
"Communicable & other Group I": "48.5"
},
"United Arab Emirates": {
"Noncommunicable diseases": "546.8",
"Injuries": "31.5",
"Communicable & other Group I": "35.6"
},
"Lebanon": {
"Noncommunicable diseases": "384.6",
"Injuries": "40.6",
"Communicable & other Group I": "30.5"
},
"Saudi Arabia": {
"Noncommunicable diseases": "549.4",
"Injuries": "41.1",
"Communicable & other Group I": "71.3"
},
"Iran (Islamic Republic of)": {
"Injuries": "74.9",
"Communicable & other Group I": "56.2",
"Noncommunicable diseases": "569.3"
},
"Iraq": {
"Communicable & other Group I": "87.0",
"Noncommunicable diseases": "715.5",
"Injuries": "128.5"
},
"Qatar": {
"Communicable & other Group I": "28.3",
"Injuries": "41.0",
"Noncommunicable diseases": "407.0"
},
"Afghanistan": {
"Communicable & other Group I": "362.7",
"Injuries": "169.2",
"Noncommunicable diseases": "846.3"
},
"Somalia": {
"Noncommunicable diseases": "550.7",
"Communicable & other Group I": "927.2",
"Injuries": "188.5"
},
"Kuwait": {
"Communicable & other Group I": "82.5",
"Injuries": "25.4",
"Noncommunicable diseases": "406.3"
},
"Oman": {
"Injuries": "52.8",
"Noncommunicable diseases": "478.2",
"Communicable & other Group I": "84.2"
},
"Tunisia": {
"Noncommunicable diseases": "509.3",
"Communicable & other Group I": "65.0",
"Injuries": "39.1"
}
}
};
var points = [],
region_p,
region_val,
region_i,
country_p,
country_i,
cause_p,
cause_i,
cause_name = [];
cause_name['Communicable & other Group I'] = 'Communicable diseases';
cause_name['Noncommunicable diseases'] = 'Non-communicable diseases';
cause_name['Injuries'] = 'Injuries';
region_i = 0;
for (var region in data) {
region_val = 0;
region_p = {
id: "id_" + region_i,
name: region,
color: Highcharts.getOptions().colors[region_i]
};
country_i = 0;
for (var country in data[region]) {
country_p = {
id: region_p.id + "_" + country_i,
name: country,
parent: region_p.id
};
points.push(country_p);
cause_i = 0;
for (var cause in data[region][country]) {
cause_p = {
id: country_p.id + "_" + cause_i,
name: cause_name[cause],
parent: country_p.id,
value: Math.round(+data[region][country][cause])
};
region_val += cause_p.value;
points.push(cause_p);
cause_i++;
}
country_i++;
}
region_p.value = Math.round(region_val / country_i);
points.push(region_p);
region_i++;
}
var chart = new Highcharts.Chart({
chart: {
renderTo: 'container',
events: {
redraw: function () {
var rootNode = this.series[0].rootNode;
if (rootNode === '') {
alert(' NO DRILLED - LEVEL 0 ')
} else {
if (rootNode.split('_').length == 2) {
alert(' DRILLED - LEVEL 1');
} else if (rootNode.split('_').length >= 2) {
alert(' DRILLED - LEVEL 2');
}
}
}
}
},
series: [{
type: "treemap",
layoutAlgorithm: 'squarified',
allowDrillToNode: true,
dataLabels: {
enabled: false
},
levelIsConstant: false,
levels: [{
level: 1,
dataLabels: {
enabled: true
},
borderWidth: 3
}],
data: points
}],
subtitle: {
text: 'Click points to drill down. Source: WHO.'
},
title: {
text: 'Global Mortality Rate 2012, per 100 000 population'
}
});
});