Making all in settings
make[2]: Entering directory `/home/devdd/workspace/xfce/xfce4-session/settings'
  GEN    xfce4-session-marshal.c
glib-genmarshal --prefix=xfce4_session_marshal xfce4-session-marshal.list --body >> xfce4-session-marshal.c
  GEN    stamp-xfce4-session-marshal.h
echo timestamp > stamp-xfce4-session-marshal.h
  GEN    xfsm-client-dbus-client.h
  GEN    xfsm-manager-dbus-client.h
make  all-am
make[3]: Entering directory `/home/devdd/workspace/xfce/xfce4-session/settings'
  CC     xfce4_session_settings-main.o
main.c: In function ‘main’:
main.c:110:33: error: ‘xfce4_session_settings_ui’ undeclared (first use in this function)
main.c:110:33: note: each undeclared identifier is reported only once for each function it appears in
main.c:111:33: error: ‘xfce4_session_settings_ui_length’ undeclared (first use in this function)
make[3]: *** [xfce4_session_settings-main.o] Error 1
make[3]: Leaving directory `/home/devdd/workspace/xfce/xfce4-session/settings'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/devdd/workspace/xfce/xfce4-session/settings'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/devdd/workspace/xfce/xfce4-session'
make: *** [all] Error 2

In main.c that in xfce4-session/settings including xfce4-session-settings_ui.h but it's empty.
I think it must be generate from xfce4-session-settings.glade, but I don't know why it's not happen.