function OpenForm(url,w,h)
{
LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;

TopPosition = (screen.height) ? ((screen.height-h)/2)-20 : 0;

settings =
'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars=no,location=no,resizable=no,statusbar=no,menubar=no';

mypage = url;
window.open(mypage,'Form_Trabajo',settings);
}