Undo/Ctrl-Z function is not working as expected

[holgerschillack]

When using autocomplete on e.g. the ":smile:" symbol in the example the input history gets deleted. So Undo/Ctrl-Z only works back to the last autocomplete action.

Repro steps:

1. Use the example codepen https://codepen.io/jukben/pen/bYZqvR
2. type something, then type ':smile' and choose autocomplete, then type again something
3. Now you can only undo your typings until the last autocomplete value was inserted with ctrl-z

Is there a solution to get the expected behaviour, as like in the moncao editor, so the autocomplete values get 'un'-inserted and so on?