Clarification:

In the appearance options I want
* no icons, no text and no window scetches (i.e only show the cell colour)

The Pager will then simply be a matrix of rectangles, where one rectangle show the active desktop position.
(since nothing is shown within the cell, naturally you won't be able to e.g. drag and drop a window to another desktop, all you can use it for is to see where you are and to pick another desktop by clickin on it)

I use Dexpot + DexGrid to have a 4x3 matrix of desktops.

I would like to be able to size a Desktop Preview as a 4x3 pager at my bottom right corner, and only show the active/inactive cellcolours.

I.e. in the options for the Desktop Preview I want to add:

* no icons
* no text

This way, I will have a Pager with 4x3 squares, all colored with the inactive backround colour except for the active square.