Collab undo history and lists

[johngodley]

There seems to be a problem with undo history and lists. To reproduce:

• With collab mode enabled (you don't need a peer), create a list
  
• On the last line press enter to escape out of the list
  
• Type some characters slowly so they each get an undo history event
  
• Undo each character and undo back into the list. When you transition from the paragraph to the list the selection point disappears and you have lost your redo history
  

I'll note that sometimes, depending on a situation I don't understand, I am able to briefly get undo or redo to work. However, it then goes into another situation I don't understand and stops working.

[johngodley]

Noting that I now can't get this to happen. Investigating!

[johngodley]

I'm not able to reproduce the loss of undo history anymore. However, with collab enabled when you undo from the paragraph into the empty list item the focus jumps out of the editor. Without collab this doesn't seem to happen. I've seen a similar problem where if you undo beyond the start of the history the focus would jump to another element. I wasn't able to find the underlying problem there, and solved it with some CSS that hid the element it was focussing on.

[johngodley]

The focus one I've narrowed down in #138