Usability: So, I’ve just found out about a useless feature of my microwave oven the hard way. The microwave’s manual notes:
Demo Mode
The Demo Mode is ideal for learning how to use the microwave oven. When set, functions can be entered without actually turning on the magnetron. The microwave oven light will come on, the fan will run and, if on, the turntable will rotate.
To Turn On/Off: The microwave oven and Timer must be off. Touch and hold TIMER SET.OFF for 5 seconds until 2 tones sound and ‘d’ appears on the display. Repeat to turn off and remove ‘d’ from the display.
Great! How useful! What a friendly UI! A tiny ‘d’ that indicates that, although your microwave looks like it’s cooking away, it’s actually doing nothing.
If you ever want to prank a friend with a Whirlpool oven, I’d recommend this one ;)