function showLoading() {
	var loadingLayer = $('<div id="loading_layer"></div>');
	var loadingBox = $('<div id="loading_box"></div>');
	loadingBox.append('<img src="' + webPath + 'templates/default/images/loading_transparent.gif">Loading...Please wait');
	$('body').append(loadingLayer);
	$('body').append(loadingBox);
	
	$('#loading_layer').width($(document).width());
	$('#loading_layer').height($(document).height());
	var boxWidth = $('#loading_box').width();
	var boxHeight = $('#loading_box').height();
	var boxLeft = parseInt(($(window).width() - boxWidth) / 2) + $(window).scrollLeft();
	var boxTop = parseInt(($(window).height() -boxHeight) / 2) + $(window).scrollTop();
	$('#loading_box').css('left', boxLeft);
	$('#loading_box').css('top', boxTop);
	
	$('#loading_layer').show();
	$('#loading_box').show();
}

function hideLoading() {
	$('#loading_layer').remove();
	$('#loading_box').remove();
}

function showAlert(message, callback) {
	var alertLayer = $('<div id="alert_layer"></div>');
	var alertBox = $('<div id="alert_box"></div>');
	alertBox.append('<div style="padding:20px;">' + message + '<br /><br /><input type="button" onclick="hidealert(' + callback + ');" value="OK"></div>');
	$('body').append(alertLayer);
	$('body').append(alertBox);
	
	$('#alert_layer').width($(document).width());
	$('#alert_layer').height($(document).height());
	var boxWidth = $('#alert_box').width();
	var boxHeight = $('#alert_box').height();
	var boxLeft = parseInt(($(window).width() - boxWidth) / 2) + $(window).scrollLeft();
	var boxTop = parseInt(($(window).height() -boxHeight) / 2) + $(window).scrollTop();
	$('#alert_box').css('left', boxLeft);
	$('#alert_box').css('top', boxTop);
	
	$('#alert_layer').show();
	$('#alert_box').show();
}

function hidealert(callback) {
	$('#alert_layer').remove();
	$('#alert_box').remove();
	if(callback) eval(callback);
}