When there's an Unknown Type like error some of the suggested solutions in Eclipse's tooltip are clipped like shown in the screenshot. Valid and invalid ones being nicely interwoven, the cut off entries don't seem to occur in any particular order.
The 'clippsed link is still working though - even if it's hard to guess beforehand what it has up its sleeve.
The string's length alone is not causing this since some strings longer than clipped ones are fully shown.
I'm running Eclipse Juno on fully updated Kubuntu and tried various themes inside Eclipse (GTK, Classic, Default Theme).