Windowed mode lets you run NWN in a window rather than full screen, though you can't shift the viewpoint by mousing off the screen.
Edit the file "nwn.ini" using a text editor such as Notepad.
Change "FullScreen=1" to "FullScreen=0".
Add the line "AllowWindowedMode=1" immediately after "Fullscreen=0"
To enter windowed mode from full screen mode, press ALT-ENTER.