[EDIT] If you had problems compiling before, try again , i just added the gtk dependencies to the instructions
You can simply compile it yourself, its very easy. Go get the source here and extract it somewhere . Copy the gtkmenubar.diff attached in the first post inside the gtk folder you just decompressed, open a terminal there and type:
Install the macmenu applet posted by Flargen , add it to your panel, logout , relogin and you are set .
sudo apt-get install pkg-config libjpeg62-dev libpng12-dev libtiff4-dev libfreetype6-dev fontconfig gettext libglibmm-2.4-1c2a libglibmm-2.4-dev libpango1.0-0 libpango1.0-dev libatk1.0-0 libatk1.0-dev libgtkmm-2.4-1c2a libgtkmm-2.4-dev
patch -p0 < gtkmenubar.diff
sudo make install