qtoctave -neither qt4 nor qt5

[sibu]

Greetings,



Im attempting to compile octave  with the qtOctave interface.  My computer has 
these:

--gcc-4.9.2, 
--linux-4.0 
--cpu  -qadcore amd64 
--OS=blfs
--qt-5.4.1  (as /opt/qt5) and qt-4.7.3  ( as /opt/qt4) 

I tried octave-3.8.2, octave-4.0.0-rc4, and octave from the mercurial 
repositiry 17thMay2015 with the following results:-
--if PKG_CONFIG_PATH is set to /opt/qt5/lib,  qt is not detected AND  even if  
QT_LIBS and QT_CFLAGS envars are set.

--If PKG_CONFIG_PATH is set to /opt/qt4/lib   qt is detected   but the build 
ends like so:-
#########################################
In file included from src/settings-dialog.cc:31:0:
src/ui-settings-dialog.h:13:29: fatal error: QtWidgets/QAction: No such file 
or directory
 #include <QtWidgets/QAction>
                             ^
compilation terminated.
Makefile:3805: recipe for target 'src/src_libgui_src_la-settings-dialog.lo' 
failed
#########################################
My initial checks with qt documentation suggests that there is
 no /opt/qt4/include/QtWidgets  in any qt4 installation
It appears to be a recent development for qt5

I also read this post 
http://savannah.gnu.org/bugs/?40252
http://hg.savannah.gnu.org/hgweb/octave/rev/d58ba8b9f709

where it appears theat qt5 support has been temporarily rooled back for 
qtOctave.  If this is so it would appear that   debris of the roolback remain  
( i.e. qt5 headers are still required though  the configure script has been 
doctored not to   detect a qt5 instalation ... or something like so).

I would be grateful for advice and hopefully a fix to get qtOctave  ( using 
qt4 or qt5 ) compiled.

Thanks in advance.

Yours sincerely

SibuXolo