Please see the following scenarios, can they be treated as a bugs?
Scenario to reproduce:
1) Type some line of the text
2) Delete some count of characters from the end of line using the backspace
3) Click "Undo"
Result:
the whole line is deleted
When expected:
Deleted characters come back
Separate situation occurs with line breaks:
1) Insert some line breaks
2) Delete last one using backspace
3) Click Undo
Result:
Nothing happens
When expected:
Deleted line break comes back
Scenario to reproduce:
1) Type some line of the text
2) Delete some count of characters from the end of line using the backspace
3) Click "Undo"
Result:
the whole line is deleted
When expected:
Deleted characters come back
Separate situation occurs with line breaks:
1) Insert some line breaks
2) Delete last one using backspace
3) Click Undo
Result:
Nothing happens
When expected:
Deleted line break comes back