HI Marius,

as it happens, I have been doing some VM work recently that will eventually make it into MetaMod and make it much easier to achieve this...

Meanwhile, I think this will do what you want:

$cart = @$_SESSION['cart'];

if ($cart == null or @$cart["idx"] == 0) {

  return XXX; // replace XXX with shopping cart module id

}

Bear in mind though, that with VM you can usually add items to the cart without doing a page refresh. (it adds via ajax). So without a page refresh, this code will not be run, and there won't be a shopping cart module on the page even though there may be products in the cart, until the page is refreshed somehow.

Just something to watch out for...

Cheers,
Stephen

You're welcome.