Mousing over a spell in your knowledge book or hotbar just displays a little sliver of a box with no information in it now. The examine window, when you right-click and hit examine, also appears to be missing some information like the name of the spell. It does this both on Win32 and Linux servers. Mousing over macros or emotes display the information just fine, so it's just spells/combat arts/abilities minus Melee Attack, Ranged Attack.

I have noticed this as well when I was testing the new mount LUA.

Should be fixed.