GetWindow function retrieves a handle to a window that has the specified relationship (Z-Order or owner) to the specified window. This is a simple wrapper around Win32 function.
Handle to a window. The window handle retrieved is relative to this window, based on the value of the uCmd parameter.
Specifies the relationship between the specified window and the window whose handle is to be retrieved. There are quite a few possibilities. Check function's documentation on MSDN.