function openvenster(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=840,height=770,screenY=100,screenX=20,top=100,left=20');
}

function openvenster2(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,width=550,height=750,screenY=250,screenX=100,top=100,left=250');
}

function openvenster3(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=550,height=650,screenY=20,screenX=20,top=20,left=20');
}

function openvenster4(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=no,width=580,height=180,screenY=200,screenX=200,top=200,left=200');
}

function openvenster5(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=1040,height=770,screenY=10,screenX=10,top=10,left=10');
}

function openvenster6(URL) 
{
window.open(URL,'','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=460,height=840,screenY=20,screenX=20,top=20,left=20');
}