A UI needs to be consistent for like functions across applications. This doesn't however mean that all applications regardless of function and visual characteristics must use an identical UI. Absolute contraints on the UI will result in compromises that favor some applications and burden others. How an individual application is used is an important consideration for picking the best UI. One of the worst examples of imposing a UI is the Apple's one button mouse. Would you want to replace the steering wheel and pedals of your car with knobs and buttons because that what your car radio has.