GetDlgItem
You can use the GetDlgItem function with any parent-child window pair, not just with dialog boxes. As long as the parent window and the child window has a unique identifier, GetDlgItem returns a valid child window.
Window GetDlgItem( int nChildWinID )
If the function succeeds, the return is the window of the specified control.
If the function fails, the return value is NULL, indicating an invalid dialog or a nonexistent control.
origin.h