Start with a blank post -
Put your cursor in the post area. Click the ordered list icon. And your cursor does not return to the position where it was when you clicked the ordered list icon. Instead if you keep typing it will be added to the post title.
BUT, the cursor isn't in the post title, so if you hit backspace to try to remove the characters which are getting added to the post title, most browsers will consider the backspace key as a click of the back button and try to navigate you away from your new post.
Thankfully WP prompts you so you won't lose anything, but either way it's easy to see that this functionality is wrong and that focus shouldn't be lost when you click one of the list buttons. The cursor should be placed back in the post section at the point of the first item in the new list.