Window Always as forground

Did you see the attached jpeg file....??? Any way i'll explain..

I want my Application say AddApp to be at the Topmost.. I have achived it...

Now the problem is when i maximize other applications ... for example Windows Explorer.. it goes behind my AddApp, as it is supposed to go..

But i dont want this to happen.. I want my Windows Explorer or any other window to get maximized or rather resized only till the bottom of my AddApp..

Please see the attached file....

Thanks,
Pradeep