When managing  a character, I found I had to open and close this window often.

1. There should be 3 buttons at the bottom, Apply, OK, Cancel. or Apply, Done, Cancel. 
   1. OK/Done should work as Apply does today.
   2. Cancel should work as it does today
   3. Apply should apply the current changes and keep the window open.
2. When selecting a level in XP mode, the page should update in-place with the current XP and Next Level XP appropriate for the currently selected level.
3. When the focus is xp-manager-change-input, the enter/return key should work as "apply" above.

To avoid opening another thread on this topic, I'll just post here:

After leveling a character in the xp manager, it should either take you directly to the edit page or a box should pop up to give you the option to go to the edit page when you click "ok". The current system is unintuitive and I almost reported it as a bug last night until I found that going to the edit page allowed me to choose new abilities. 

I agree. I got very confused when my lvl 5 character reached lvl 6, but it's cleric level stayed at 5. Probably smart to offer a simple way to "multi-class or not" on level-up.