Hello.
First, move qtoctave.desktop from /usr/share/applications to /usr/share/applications/hildon or something like this to see it in Hildon menu.
Second, add gnuplot as deb dependency, then plot() will work in QtOctave.
Third, find out why buttons have no images. It should be not difficult to fix.

Finally, thanks for porting Octave and QtOctave!