1. A method of implementing a graphical user interface (GUI) for a program executing on a computing device, said method comprising: providing a first GUI control for adjusting a first value of a first user adjustable parameter; providing a second GUI control for adjusting a second value of a second user adjustable parameter, said second GUI control adjusting the second value independently of the first value; and providing a lock-in control that, when activated, prevents the second GUI control from adjusting the second value but locks the first and second values together so that adjustments to the first GUI control adjust the first value and in turn the second value.