When I clicked "Undo", the Screen.Initialize event got deleted, and I couldn’t redo it. How is that even possible?
I didn’t make any changes to the Initialize event, yet it was still deleted.
What should I do? There are a lot of processes inside it. 
Keep trying Undo ?
or
Restore your last backup aia that you made containing all those important processes?
If a bug, are you able to replicate this behaviour in a test project ?
Yes, I tried Undo, but the Screen.Initialize event didn’t come back.
Unfortunately, I didn’t make any recent .aia backup before this happened 
Is there any other way to recover it? That block had a lot of important logic inside.
Check it is not actually deleted
Clean up blocks, or reduce screen size to see ALL blocks, just in case it moved somewhere?
checked all. but did not find it
Expensive lesson!
Make a set of procedures and call these from initialize. It will result in much cleaner and probably shorter code. And make frequent backups by using save as… It will give you a trail of versions you can go back to.
Fortunately, I had a backup. But is this a bug?
I also encountered a few other bugs:
- When using the join block or the make a list block, if I try to delete or add a string/item, sometimes the entire socket disappears.
- When I try to move some blocks, even after releasing the mouse button, the block keeps following the mouse pointer. I have to reload the website to fix it.
...
not recent, 3 days older. I had to spend a lot of time fixing things afterward.
You could drag in the named png files of your procedures, events, and global inits you downloaded as you code.
They make fine grained reusable backups.