Windows 7 - Change taskbar behavior

Hello,
I need to allow full screen Windows applications overlapping task bar under Windows 7.
The "auto hide" is not the option due to user requirements I don't want to describe here.
One possible solution is to change the code of those applications to allow them overlapping task bar, but it will imply a lot of work as we have many of them already running at customer's side.
The best would be just to remove programmatically the "topmost" style of task bar window, but my code failed to do that with the error 0x00000005 "Access denied".

Does anyone know any solution for that?
Regards
Nik

Not sure if this is what you are looking for:

Taskbar Always On Top - Disable or Enable

Lemur,
Thanks for your answer.
I'm aware of this solution, the problem however is that we cannot use third part solutions without having their source code.
Besides that, as far as I understand this solution changes the behavior of "auto hide" option that we don't want to touch.
Thanks anyways
Nik

Okay, I'll state something dumb. You could drag the task bar to the left or right side. Okay, I said it. LOL.