Problem/Motivation
As a great man said :<dawehner> DuaelFr: this always confused me, but I am biased as the code is in my brain
From an user point of views, the fact is that "Display 'more' link only if there is more content" is not really natural to understand and its description does not help a lot.
From a developper point of view, '#default_value' => !$this->getOption('use_more_always'), looks like a double negation.
In each case, this can lead to a lot of confusion.
Proposed resolution
Change title to "Always display the 'more' link"
Change the description to "Check this to display the 'more' link even if there are no more items to display."
Change the default value handling to remove the negation
Change the option save to remove the negation
User interface changes
Invert the use_more_always checkbox. It will have to be checked for the option to be active.
Credit
This issue was covered during the first Drupal Sprint of Montpellier (France).