--- /usr/portage/dev-libs/libnsfb/libnsfb-9999.ebuild	2012-07-18 10:25:38.000000000 +0200
+++ libnsfb-9999.ebuild	2013-02-17 15:14:35.962557033 +0100
@@ -14,14 +14,11 @@
 LICENSE="MIT"
 SLOT="0"
 KEYWORDS=""
-IUSE="static-libs"
+IUSE="static-libs sdl vnc xcb"
 
-RDEPEND="media-libs/libsdl
-	net-libs/libvncserver
-	x11-libs/libxcb
-	x11-libs/xcb-util
-	x11-libs/xcb-util-image
-	x11-libs/xcb-util-keysyms"
+RDEPEND="sdl? ( media-libs/libsdl )
+	vnc? ( net-libs/libvncserver )
+	xcb? ( x11-libs/libxcb x11-libs/xcb-util x11-libs/xcb-util-image x11-libs/xcb-util-keysyms )"
 DEPEND="${RDEPEND}
 	virtual/pkgconfig"
 
@@ -46,6 +43,15 @@
 	echo "Q := " >> Makefile.config.override
 	echo "CC := $(tc-getCC)" >> Makefile.config.override
 	echo "AR := $(tc-getAR)" >> Makefile.config.override
+
+	# replace auto-detection by USE flags for sdl, vnc, and xcb
+	local u a=available n=NSFB_
+	for u in VNC SDL XCB
+	do
+		use ${u,,} && eval $u=yes
+		sed -e "/$a,$n$u/s+\(^.*$\)+#\1\n$n${u}_${a^^} := ${!u:-no}+" \
+			-i Makefile || die
+	done
 }
 
 src_compile() {