My colleague Daniel Westerblom at WM-Data asked my a question concerning the fake lookups that I have referenced bellow and that I know are commonly used by many partners. The question was if these customizations are supported.
When I was at convergence I asked this explicit question to, I think it was, Clint Warriner (CRM Escalation Engineer at Microsoft Support) and he gave me confirmation on what I had suspected, that these customizations are not supported. They fall under the last point concerning unsupported customizations described in the SDK:
"The use of custom HttpModules to inject HTML/DHTML into the Microsoft CRM Forms."
Since the HTML DOM is modified, this is not supported.
The reason for this is most probably that Microsoft might choose to change this in future releases of CRM (for instance CRM 4.0) and might also have internal scripting references to objects they expect to be there according to the standard HTML DOM.
I don't know if these fake lookups will upgrade from CRM 3.0 to 4.0 without problems. If you have any experience of it, please let me know.
If you have any comments on this subject, please feel free to comment bellow. I always publish comments that concern the subject and are not directly offensive. (I have activeted moderation on comments just to avoid comment spamming).
Microsoft Dynamics CRM Consultant