The number of undo steps should be the same as for redo.
Platform: Windows (QtNetwork4.dll from Qt distribution)
Steps to reproduce bug:
1. New text file
2. Insert some text e.g. "Mens sana in corpore sano"
3. Select "corpore"
4. Hit Enter
At step 5 instead of just one undo, there are three operations needed to get to previous state.