I’m sure most of us would love an undo button… so many times I accidently delete something and have to remember what it was.
How about it @Simeon? 
There already is an undo button. Zit on the numeric keyboard behind where the Z and X keys are. What would be nice is for the undo button to keep information after the program is executed. It looks like once a project is run, the undo information is erased.
Undo button at lower left of number keyboard.
If using a Bluetooth keyboard, turn on screen keyboard.
On my Logitech keyboard, press fn-3 to get on screen keyboard.
If you press the .?123 key in the bottom left, the area where the Z and X keys were turns into an undo button. I think a more consistent version is coming soon though, can’t remember what Simeon said.
Also, please search the forums before asking stuff like this. It’s been asked many times, and it gets a bit old answering the same questions over and over again.
@Simeon How about adding the answer to the FAQ? 
Awesome, never saw that button. Thanks guys!
@SkyTheCoder If it gets old answering the same question over and over, why did you answer this one when I responded to it 42 minutes earlier. I have no problem answering the same questions because some of the new users might benefit from it, not knowing how to search the forum.
@dave1707 I didn’t understand “zit on the numeric keyboard,” and I wanted to be specific about where to find to it.
@SkyTheCoder I hate it when the auto complete changes things that I type. I didn’t realize that there was a mistake, and I know you don’t like mistakes.
@dave1707 I’m fine with mistakes, I just didn’t understand what you said. Don’t worry, AutoCorrect bugs me all the time, too. Anyways, this is getting a bit off-topic.
Also if you’re using the bluetooth keyboard you can press CMD+Z.
As well as using shift + arrows to select and CMD+X, CMD+C, CMD+V for cut, copy, paste.
Originally there used to be a “shake to undo” feature that’s still there.
I’d also never seen the undo on the numeric keypad 