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I tried to find and I failed...
does the program has an undo key\shortcut?
I'm afraid there's no comprehensive Undo function, except for in the text editor components, where you can use Control + Z as you are probably used to.
The reason is that it's quite tricky to implement proper Undo functionality for the GUI-based parts (i.e. something that helps rather than disrupts things), although it would of course be very convenient.
There's much bigger issues in the world, I know. But I first have to take care of the world I know.