I encode all of my blu ray mkv files with chapter markers from the chapters on the DVD/blu ray disk using handbrake (note that this is now default behavior in handbrake). They make it handy to skip intro scenes in TV series or jump to specific scenes in movies. Plex currently does not read these chapter markers and playing on a tablet or PC requires you to randomly guess where to skip ahead or jump ahead in 30 second incriments using the button, which is very cumbersome.
I'm not looking for anything fancy like pictures or menus simlar to a DVD or blu ray (part of a different feature request on this forum). Just the code to read the chapter markers in mkv and mp4 containers and two buttons to navigate added to the player: 1) skip forward one chapter and 2) skip backward one chapter.