See for details:

http://lists.altlinux.org/pipermail/devel/2009-March/167877.html

diff --git a/fluxbox/configure.in b/fluxbox/configure.in

index 916f4c8..7b3c6c7 100644

--- a/fluxbox/configure.in

+++ b/fluxbox/configure.in

@@ -444,8 +444,8 @@ if test x$enable_imlib2 = "xyes"; then

       [

          IMLIB2=true

          AC_DEFINE(HAVE_IMLIB2, [], [Imlib2 support])

-         IMLIB2_LIBS=`imlib2-config --libs`

-         IMLIB2_CFLAGS=`imlib2-config --cflags`

+         IMLIB2_LIBS=`pkg-config imlib2 --libs`

+         IMLIB2_CFLAGS=`pkg-config imlib2 --cflags`

          LIBS="$LIBS $IMLIB2_LIBS"

          CXXFLAGS="$CXXFLAGS $IMLIB2_CFLAGS"

        ], [ AC_MSG_RESULT(no)]