I have a problem with 5.9, not existing on 5.5, do you see it also on linux? In xmaxima, if I type something like 4*5; in the LOWER window and then go to edit, change to maxima and chose mark for evaluation I get an error message about a ] after quote instead of a space. This makes the lower window useless for "notebook" type use a la Mathematica. Any comments?