Went through the whole quest, killed 3 dragons,
clicked on a gold pile, and was shunted out of the black dragon area without even gettign the chest.
Very upset that a GM stated it was not possible to get back in in ANY way, despite my party members still being in the instance after waiting for 5 minutes for a GM to show up. (Very thankful it was only 5 minutes.)
A simple "would you really like to leave" dialog box would have REALLY helped there. There's no way to prevent going out of the area.
Probably wasn't a scale in there for me with my luck today, but it would have been better to KNOW that.
"Once the end boss is defeated the instance is considered closed to the players who have left. Regretfully there is nothing we can do in regards to this issue."
I didn't exactly leave of my own free will, and it's easy to check the player log to verify that I was actually there killing the dragon with my party.