In this example user input is locked for VFP application only. This function works differently then the BlockInput does. The latter locks the window for all processes not just for the active process and thread.
With EnableWindow you can effectively lock a VFP application. But it is more like "you lock the door and throw away the key". To unlock it use the Task Manager, or beforehand submit the instructions to some other application along with the corresponding HWND.
Applied to windowed controls this function can enable or disable them.