hi Mark,
We (my company) have developped some special features in the POS for our customers.
I've made a tutorial about how to make a module from A to Z and how to modify the POS.
I've added some features to the POS.
Maybe it's not exactly what you need, but that may be a first step for you to develop such features you need.
The tutorial is in french (I haven't translated it yet) but maybe you can go with Google translate or something like that.
I have not enough karma for now , but you should find it around there:
http ://thierry-godin.developpez.com/openerp/tutoriel-openerp-realisation-module-web-pour-point-vente/
And now I made an English version here :
http ://thierry-godin.developpez.com/openerp/tutorial-module-creation-pos-modification-english-version/
I tried a basic example before and it should work for you too.
is it possible to open the new window in the second monitor?
Hy Marc, Did you get the solution. I want the same solution. will appreciate your help. Thanks