function initialize(){
    hideLoadingImage();
    updateChart();
}

//Update the chart according to user selection
function updateChart()
{
    
    var number=0;
    var length=m1_multiple.options.length;
    for (var i = 0; i < length; ++i){
        if(m1_multiple.options[i].selected){
            if(m1_multiple.options[i].value!=""){ 
                number++;
            }
        }
    }
    if(number==0) {
        alert("Please select months.");
    }else{
    displayLoadingImage();
    
    //
    //we encode the values of all form elements as query parameters
    //
    var elements = document.generalForm.elements;
    url =elements.action.value + "?";
    for (var i = 0; i < elements.length; ++i)
        {
            var e = elements[i];
            if (e.name == "m1_multiple"){
                for(var j=0;j<e.options.length;j++){
                    if(e.options[j].selected){
                        url = url + e.name + "=" + escape(e.options[j].value)+"&";
                    }        		 
                }
            }
            if(e.name != "m1_multiple"){
                url = url + e.name + "=" + escape(e.value)+"&";
            } 
            
        }
        url = url + "D=dummyParameter";
        
        //Now we update the URL of the image to update the chart
        // document.write("number_of_months_selected="+number_of_months_selected);
        // document.write(url);
        getChart(url);
    }
}

Event.observe(window, 'load', function() {
    Event.observe(document.generalForm.m1, 'change',    function(){
        if(document.generalForm.m1.value=="") alert("Please select months.");
    });
});