it turned that I was not aware of the problem with readline. However, it is quite questionable if putting a terminal emulation into a window can be a solution for a GUI - I don't think so. What Octave is missing is some way of communicating to it not using pipes or a terminal emulation, but that is not the case (I felt pipes were not the right thing, but I thought QtOctave was considered as the "right thing"). Maybe it is a better idea to integrate such a thing into Octave itself - and then building some GUI on top of it.
-- Software Development == Church Development Step 1. Build it. Step 2. Pray.