OSX provides an option to have a pop-up menu appear providing accented characters when a character is held down (as opposed to repeating the character.) This behavior is apparently not available in LibreOffice. I posted to the users group to see if there was any intelligence available as to whether LO intentionally defeated this OS option or whether this was just incidental to some other aspect of the program and received no substantive responses.
So, the first question I have of course is whether there is some documentation of how LO changes the keyboard behavior on OSX, secondly, whether the behavior observed is consistent with the design of the software, and third, whether there is some reason that the OS is barred from managing this behavior and if not whether the OS behavior could be passed through.