To set up a new UI window

Launch interface builder.
In Choose a Template, click Mac OS X, and Window, Product: Cocoa; click Choose.
Size the Window.
Add OK/Cancel buttons from Library, set up all other elements of the window.
Click on File's Owner.
Use information (i) palette and for Class, name a new class,
e.g. WebPEncodeQualityController.

Create corresponding header file WebPEncodeQualityController.h

Add IBOutlet properties for each interface object that you need to reference
from code.

Add actions for each message that you want to receive from interface objects.

When the class is finished, Read Class Files in IB,
specifying the new class header.

Control-click on File's Owner.

Drag to connect outlets with objects,
and actions with sending selectors.