audio-recorder/src/settings.c:715: undefined reference to `gtk_widget_set_margin_start'

Failed make
On running make

settings.o: In function `win_settings_show_dialog'
/home/xxx/audio-recorder/src/settings.c:715: undefined reference to `gtk_widget_set_margin_start'
/home/xxx/audio-recorder/src/settings.c:730: undefined reference to `gtk_widget_set_margin_start'
/home/xxx/audio-recorder/src/settings.c:748: undefined reference to `gtk_widget_set_margin_start'
/home/xxx/audio-recorder/src/settings.c:773: undefined reference to `gtk_widget_set_margin_start'
collect2: error: ld returned 1 exit status
make[1]: *** [audio-recorder] Error 1
make[1]: Leaving directory `/home/xxx/audio-recorder/src'
make: *** [install-recursive] Error 1

gst-launch-1.0 --version

gst-launch-1.0 version 1.4.3
GStreamer 1.4.3
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

everything else appears to be installed corredtly

Ubuntu 14.04 LTS amd64
all updates / upgrades done

any suggestions ?

edit:
further investigation reveals 'make' generates a warning:

settings.c: In function ‘win_settings_show_dialog’:
settings.c:715:5: warning: implicit declaration of function ‘gtk_widget_set_margin_start’ [-Wimplicit-function-declaration]
     gtk_widget_set_margin_start(label0, 3);
     ^

haven't yet found where the declarations are!

edit 2:
forget this, appears that 1.6 is not going to work on Ubuntu 14.04, installed 1.4 instead