I got some code I need to change. it is build by others, and not very neat...

There is a javascript tabcontrol, containing 4 tabs, which contains gridviews. All the 4 gridviews are build during the load of the page, but I want them to load, when you activate the tabs (as it is possible to watch the side, while you don't need the specific gridviews to see)

So, my question is: how to call an event (that loads the gridview) from an javascript tab?

how the tabs are generated: (generated code, I know, horrible)

var obj = 0;
var oid = 0;
var otb = 0;
var myTabs = new Array();
var myTabitems = new Array();
var myTabitem = new Array();
var myTabContent = new Array();
var myLists = new Array();


function showTabContent(tab)
{
    tb = tab.obj;
    id = tab.nr;
    if (myTabs[tb].oid != -1)
    {
        myTabs[tb].myTabContent[myTabs[tb].oid].style.display = 'none';
        myTabs[tb].myTabitem[myTabs[tb].oid].className -= " active";
    }
    myTabs[tb].myTabContent[id].style.display = 'block';
    myTabs[tb].myTabitem[id].className += " active";
    myTabs[tb].oid = id;
}

function boTabs()
{
    var myBlocks = new Array();
    myBlocks = document.getElementsByTagName("div");
    var stopit = myBlocks.length;
    for (var g = 0; g < stopit; g++)
    {
        if (myBlocks[g].className == "tabs")
        {
            myTabs.push(myBlocks[g]);
        }
    }
    var stopit2 = myTabs.length;
    for (var i = 0; i < stopit2; i++)
    {
        myTabs[i].myLists = myTabs[i].getElementsByTagName("ul");
        if (myTabs[i].myLists[0].className == "tabs")
        {
            myTabs[i].myTabitems = myTabs[i].myLists[0].getElementsByTagName("li");
        }
        var stopit3 = myTabs[i].myTabitems.length;
        myTabs[i].obj = i;
        myTabs[i].myTabitem = new Array();
        myTabs[i].myTabContent = new Array();
        for (var j = 0; j < stopit3; j++)
        {
            myTabs[i].myTabitem.push(myTabs[i].myTabitems[j]);
            myTabs[i].myTabitem[j].nr = j; myTabs[i].myTabitem[j].obj = i;
            myTabs[i].myTabitem[j].onclick = function() { showTabContent(this); };
        }
        var myTabDivs = myTabs[i].getElementsByTagName("div");
        for (var j = 0; j < myTabDivs.length; j++)
        {
            if (myTabDivs[j].className == "tabcontent")
            {
                myTabs[i].myTabContent.push(myTabDivs[j]);

        } 
    }
    myTabs[i].myTabitem[0].className += " active";
    myTabs[i].myTabContent[0].style.display = 'block';
    myTabs[i].oid = 0;
    myTabDivs = null;
}
myBlocks = null;

} onload = boTabs;