At this stage, since you don't have the source code yet, I am not sure what could be happening. Have you tried using any of the SF wrapped DevEx controls from the inherited UI? Maybe the DevEx Maintenance form is a template and that is why you are getting the reference. I don't use DevEx, so I can't check it right now on my machine, I would have to ask the developers to create the test scenario to check it for you. But for the trial period, maybe you could go on and test the SF Maintenance Form and get the feeling of it, so you could have a general knowledge of what the framework could do for you.

Cheers.

I've already used the EnhancedList, and TextEdit from the SF DevEx wrapper and it works ok. I'd rather you checked with your developers for this, as the goal for our evaluation of the trial for us is to see if it will work seamlessly with our existing investment in DevExpress.

Could you post an example app that works with the EnhancedList and TextEdit but not with the Maintenance form?  Likely there is just a messed up reference somewhere, which is easy to fix once found....but hard to find without a project to look at.   That way not only can the developers take  look, but there are other users who use DevX and they can test it as well.