Forcing another EXE to have focus

What API call do I need to make to force another EXE to have focus. For exapmle in program A, when I double click an item in a listview, I want program B to become the active window.

I understand I must first check to see if program B is loaded and all that good stuff.

Use FindWindow to get the handle of the program window and then SetForeGroundWindow to set focus.

I am having the same problem in my post Maximise window.

I tried by getting the process id or window handle and then using the send message API to maximise.
try this in your appllicaton.

Thanks
Ramdas