Please describe the problem:
libgnomeui 2.24.1 is installed and libgnomeui/gnome-help.h exists:
$ ls -lah /usr/include/libgnomeui-2.0/libgnomeui/gnome-help.h
-rw-r--r-- 1 root root 1.8K 2009-04-13 16:04 /usr/include/libgnomeui-2.0/libgnomeui/gnome-help.h

pkgconfig knows how to include the proper files:
$ pkg-config libgnomeui-2.0 --cflags
-DORBIT2=1 -pthread -I/usr/include/libgnomeui-2.0 -I/usr/include/libart-2.0 -I/usr/include/gconf/2 -I/usr/include/gnome-keyring-1 -I/usr/include/libgnome-2.0 -I/usr/include/libbonoboui-2.0 -I/usr/include/libgnomecanvas-2.0 -I/usr/include/gtk-2.0 -I/usr/include/gnome-vfs-2.0 -I/usr/lib/gnome-vfs-2.0/include -I/usr/include/orbit-2.0 -I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/libbonobo-2.0 -I/usr/include/bonobo-activation-2.0 -I/usr/include/libxml2 -I/usr/include/pango-1.0 -I/usr/include/gail-1.0 -I/usr/include/freetype2 -I/usr/include/atk-1.0 -I/usr/lib/gtk-2.0/include -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/libpng12

When compiling fast-user-switch-applet 2.24.0, the compile complains about missing libgnomeui/gnome-help.h:
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --with-gdm-config=/etc/gdm/custom.conf && make
...
Making all in src
make[2]: Entering directory `/usr/src/fast-user-switch-applet-2.24.0/src'
gcc -DHAVE_CONFIG_H -I. -I..  -DG_LOG_DOMAIN=\""Fast-User-Switch-Applet"\" -DDATADIR=\""/usr/share"\" -DORBIT2=1 -pthr
ead -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pango
-1.0 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/inclu
de/libpng12 -I/usr/include/panel-2.0 -I/usr/include/gconf/2 -I/usr/include/libbonoboui-2.0 -I/usr/include/orbit-2.0 -I
/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include -I/usr/include/libxml2 -I/usr/include/libbonobo-2.0 -I/usr/include/l
ibgnomecanvas-2.0 -I/usr/include/libgnome-2.0 -I/usr/include/bonobo-activation-2.0 -I/usr/include/gail-1.0 -I/usr/incl
ude/libart-2.0 -I/usr/include/gnome-vfs-2.0 -I/usr/lib/gnome-vfs-2.0/include -I/usr/include/libglade-2.0     -Wall -Wm
issing-prototypes -Wnested-externs -Wpointer-arith -Wno-sign-compare  -Wcast-align -Wchar-subscripts -Wsign-compare -W
no-strict-aliasing -march=core2 -m32 -pipe -DPIC -fPIC -O2 -fomit-frame-pointer -MT fast_user_switch_applet-applet.o -
MD -MP -MF .deps/fast_user_switch_applet-applet.Tpo -c -o fast_user_switch_applet-applet.o `test -f 'applet.c' || echo
 './'`applet.c
applet.c:55:35: error: libgnomeui/gnome-help.h: No such file or directory
applet.c: In function 'applet_fill_cb':
applet.c:459: warning: implicit declaration of function 'getuid'
applet.c:459: warning: nested extern declaration of 'getuid'
applet.c: In function 'help_cb':
applet.c:1109: warning: implicit declaration of function 'gnome_help_display_on_screen'
applet.c:1109: warning: nested extern declaration of 'gnome_help_display_on_screen'
make[2]: *** [fast_user_switch_applet-applet.o] Error 1
make[2]: Leaving directory `/usr/src/fast-user-switch-applet-2.24.0/src'

fast-user-switch-applet does not seem to use pkgconfig to determine the include paths.

Steps to reproduce:
1. Install dependencies of fast-user-switch-applet 2.24.0
2. Compile fast-user-switch-applet 2.24.0 using the following flags:
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --with-gdm-config=/etc/gdm/custom.conf && make
3. Run into the compile issue


Actual results:
Compilation fails

Expected results:
Compilation succeeds

Does this happen every time?
Yes

Other information:
Distribution bug reports:
Source Mage GNU/Linux: http://bugs.sourcemage.org/show_bug.cgi?id=15172
Gentoo: http://bugs.gentoo.org/show_bug.cgi?id=263367