Projected Rewards
If you complete all the quests you currently have, will you DING? The green statusbar indicates your total POTENTIAL (Projected) rewards. In other words, you have completed quests worth of 245 xp in the picture above, but you need to grind a bit more.
Turn in quests to DING!
Once you have completed enough quests, the statusbar will let you know that you will DING upon turning your quests in.
Will turning in your quests make you DING?
Track how much XP you are set to get when handing in your completed quests.