When a text includes headings that are numbered using Outline Numbering, 
then the navigator 'forgets' to put a space between outline number and the
heading. This looks strange and entices users to add a space before the heading
(which is counterproductive). 

Example (Numbers result from Outline Numbering): 
1 Introduction
1.1 First section
1.2 Second Section 

Is shown in the navigator as: 
1Introduction
1.1First section
1.2Second Section 

(I know that heavy OOo users may have become accustomed to the lack of the space
in the navigator, but the shortcoming is very obvious to any new user).