change cursor to busy while page is loading

I understand how to use javascript to change the cursor to busy while the page is making and ajax call.

However I have a page that does not use ajax, it uses a postback to reload the page. However the load is rather data intensive and it takes a few seconds. During this time the user can still click on the page. I want to turn the cursor to "waiting" so the user does not try to click on the page.

For example I have a couple of dropdowns that cause postback. I make a selection and the page loads for 3 seconds. While it loads I would like the cursor to turn to waiting so the user does not try to make a selection on a second dropdown until the page reloads.

Is this possible?

Additional Info: (simplified version of my setup)

I have a masterpage:

<form id="form1" runat="server">
<table width = "100%" bgcolor="White">
<tr><td>
<h3><asp:ContentPlaceHolder id="MAIN" runat="server"></asp:ContentPlaceHolder></h3>
</tr></td>
</table>
</form>
<script type="text/javascript">
    function cursorwait(e) {
        document.body.style.cursor = 'wait';
    }

    var fm = document.getElementById('<% =form1.ClientID %>');
    if (fm.addEventListener) {
        fm.addEventListener('submit', cursorwait, false);
    }
    else {
        fm.attachEvent('onsubmit', cursorwait);
    }
</script>

and then a page that uses the master page:

<asp:Content ID="Content1" ContentPlaceHolderID="MAIN" Runat="Server">
<table runat=server id="tb_simple_search_table" cellpadding = 0 cellspacing = 0>
<tr><td>
    <asp:DropDownList...
    <asp:DropDownList...
</td></tr>
</table>
</asp:content>