vm2.0.1 j1.7 productdetails view: first/last products aren't the correct ones

[Leridan]

I'm using VM in catalog mode and the default sort order is by ID.

I'm using four product categories, a,b,c and d

some products from a also belong to d

As this is a shop I'm setting up, the categories have been filled sequentially, ie I first created the products in a, then b, etc...

in the d category view, the dual category products from a are displayed first, then the specific d products which were created later.

incidentally, the last a product is also part of d.

Now my problem:

the last a/d product is treated as the last product, ie there is no "next product" link in its productdetails page.
the first purely d product is treated as the first product, ie there is no "previous product" link in its productdetails page.

I could write a fix for this, but I'm not familiar with vm's classes, could anyone help? specifically I need a way to retrieve the first and last products' id's from the productdetails view.

[Leridan]

sorry, it's vm 2.0.0, NOT 2.0.1
and it's J 1.7.3

[Leridan]

After upgrading to J2.5.1 and VM2.0.2, the problem persists.

It could be solved by making the first product "next neighbour" of the last, but I have no idea how to access first and last's id's.