Code Block Undo event allowed to bubble causing issues

[griffpatch]

Actual Behavior

When you press Ctrl+Z repeatedly after placing blocks, the focus will change to the sprite name, or other input boxes and undo any changes you made there too earlier. The undo even needs to be prevented from bubbling up I suspect?

Steps to Reproduce

Steps to reproduce the behavior:

1. Start a new project
2. From the coding tab, Rename the sprite to "Testing"
3. Now drop in a few blocks
4. Press Ctrl+Z a few times

At this point the focus changes back to the sprite name after one click (at the same time as the last block disappears)
Then on the second press the 2nd block disappears, but the sprite is also renamed back to "sprite1"
And on the next press the other blocks continue to disappear.

Because the blocks do get undone... you can easily have awful things happen without realising it. Also, sprite renames across sprites can be undone causing concatenation of sprite names, and all sorts of badness!

System Details

Win 10, PC