plot hangs in octave on mac os x 10.11.3

[Massimo Sorbara]

Hi,
I hope that you can help me solve this problem!  It is very frustrating. Here 
goes:

I have installed octave on a MacBook Pro (13-inch, Mid 2010) running OS X 
10.11.3.
The processor is 2.4 GHz Intel Core 2 Duo.
I installed octave using Homebrew.  In the process I also installed Xcode from 
the App Store and also installed XQuartz.
Basically I followed the procedure in 
<http://wiki.octave.org/Octave_for_MacOS_X>  and installed brew via the command 
at <http://brew.sh>.
I have executed each of the following commands:
- brew tap homebrew/science
- brew update && brew upgrade
- brew install octave
- brew tap —repair
- brew update && brew upgrade
I have also added "setenv ("GNUTERM", "X11”)” to the .octaverc file, located at 
/usr/local/share/octave/site/m/startup. 

The octave gui comes up fine. I can run basic mathematics commands.  The 
problem is in plotting.
Whenever I go to execute a plot(…) command, the system hangs and the mac 
pinwheel perpetually spins.
I need to do a force quit on the octave gui to get it to stop; nothing else 
closes the program.

I also tried the following and shown is the error message:
- brew install fltk
- fltk: This formula either does not compile or function as expected on OS X 
versions newer than Yosemite due to an upstream incompatibility.

Can you help me this plotting problem with octave on my mac solved?
Thank you.
Best regards,
Massimo Sorbara