I must host a credit card applicatoin window from the process "A" in to the primary window of the process "B", just like if "A"'s window were a MDI child window. Is possible in Home windows? Or exist some methods which may let me fake this?

Incidentally, Let me take away the title bar (or even better, all of the non-client stuff) of "A"'s window when it's embedded into "B"'s window. I guess this should be possible by fine-tuning your window styles or window classes, however i am in no way a specialist during these Win32 particulars.

You can host your window. Change A's parent HWND by calling the SetParent function against it. To alter your window styles, you should utilize the GetWindowLong/SetWindowLong pair to alter the characteristics you want to muck with.

If this sounds like another-party application (ie, not yours), then you are most likely set for a tough ride, specifically window does any theming or anything custom using its window (for instance, changes towards the drag area, etc).