Once you gain a new level and the "level up" image is hiding you portrait (top right corner) you can no longer cast any spells or use targeted items on you portrait.
This can be quite frustrating when you want to cast a healing spell or buff yourself while the screen is crowded.
As more and more players are reaching lvl 20 and since the waiting list for an ECDQ is quite long (months) I have an idea of a inventory item that will keep you from getting exp. Either it can be automaticly gain upon reaching lvl 20 or given by a DM. Since most players will probably reach lvl 22-23 (if you count the exp) they will no longer have to nag the DM's about removing exp just get their portrait back and be able to target themself using the portrait.
Im not sure how the no exp is handled when you are recovering from death and since I have no idea how the exp is handled this might be hard to do or perhaps a piece of cake for our godlike scripters