Powering on/off such a silly thing but in the world of robotics nothing is that simple!

I originally had a 2 bitmaps, one with all buttons off and one with all buttons on. Then I figured out that the ON button should always be lid because it wants your attention that you can hit that button to power it on. So I changed the background to all buttons off except that one. The fact that other buttons gets lid up (and I have a yellow warning border) is an indication that the power is really on.

I toyed with the idea to change the power button green when it is off and red when it is on, but in the end that is not a good idea because the power on or off is always a dangerous button. You don't want to power a robot off when it is busy doing something. So this one will always be red.

Also powering off is not that simple. A sequence of safety commands must be executed before the screen loses control. The robot must go to the nearest safety point before it can power off.

These safety points and actions must be known BEFORE the robot starts any motion. It must know before because when an emergency happens the robot has no time to start calculating. It should act as soon as possible  just before the powers goes out.

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Imagine a robot with a blowtorch. When you hit the power off button then you want the robot to turn that torch away from your target. The circuit that turns off that blowtorch may fail or never get the turn off signal because it is on a separate circuit. But the robot has control over its motions and move the torch away as a second fail safe mechanism

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I realize that this Thor project is not that dangerous, but the whole point in building one is to learn stuff like this would be a big giant industrial robot. Safety must be part of the design.