var win = null;
function NewWindow(mypage,myname,w,h,scroll){
LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
TopPosition = (screen.height) ? (screen.height-h)/2 : 0;
settings = 'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',resizable=no'
win = window.open(mypage,myname,settings)
}
function clearText(field){
    if (field.defaultValue == field.value) field.value = '';
    else if (field.value == '') field.value = field.defaultValue;
}