<script language="javascript" for="document" event="onkeydown">

<!--

if(event.keyCode==13 && event.srcElement.type!='button' && event.srcElement.type!='submit' && event.srcElement.type!='image' && event.srcElement.type!='reset' && event.srcElement.type!='textarea' && event.srcElement.type!='')

event.keyCode=9;

-->

</script>

function fun_tab() {  
    if (event.keyCode == 13 &&  event.srcElement.type!='submit') {  
        event.keyCode = 9;  
        }  
    if(event.keyCode == 13 && event.srcElement.type=='submit'){  
         document.form.submit();  
        }  
}