function set_size(new_size, element_id){
	if(document.getElementById(element_id)){
		// alert('setting size for ' + element_id + ' size = ' + new_size);
		document.getElementById(element_id).style.fontSize = new_size + 'px';
	}else{
		// alert(element_id);
	}
}
function get_current_size(element_id){
	var current_size = document.getElementById(element_id).style.fontSize;
	var position_px = current_size.indexOf('px');
	return current_size.substr(0, position_px);
}
function size_increase(){
	for(var i = 0; i < ar_elements.length; i++){
		if(document.getElementById(ar_elements[i]['element_id'])){
			var current_size = get_current_size(ar_elements[i]['element_id']);
			new_size = parseInt(current_size) + 1;
			set_size(new_size, ar_elements[i]['element_id']);
		}
	}
}
function size_decrease(){
	for(var i = 0; i < ar_elements.length; i++){
		if(document.getElementById(ar_elements[i]['element_id'])){
			var current_size = get_current_size(ar_elements[i]['element_id']);
			new_size = parseInt(current_size) - 1;
			set_size(new_size, ar_elements[i]['element_id']);
		}
	}
}