+# Check for gpsd support
+AC_ARG_ENABLE([gps],
+ AS_HELP_STRING([--enable-gps], [Build with gpsd support]))
+AS_IF([test "$enable_gps" = "yes"],
+ [PKG_CHECK_MODULES(GPSD, libgps >= 3.0)])
+AM_CONDITIONAL([HAVE_GPSD], test "x$enable_gps" = "xyes")
+
+# Define odd RSL install location
+AC_CHECK_LIB(rsl, RSL_wsr88d_to_radar, RSL_LIBS="-lrsl")
+AM_CONDITIONAL(HAVE_RSL, test "$RSL_LIBS" != "")
+AC_SUBST(RSL_LIBS)
+
+# Test for windowing system
+case "${host}" in
+ *mingw32*) SYS="WIN" ;;
+ *cygwin*) SYS="WIN" ;;
+ *apple*) SYS="MAC" ;;
+ *) SYS="X11" ;;
+esac
+AM_CONDITIONAL([SYS_WIN], test "$SYS" = "WIN")
+AM_CONDITIONAL([SYS_MAC], test "$SYS" = "MAC")
+AM_CONDITIONAL([SYS_X11], test "$SYS" = "X11")
+
+# Check for Mac OX
+if test "$SYS" = "MAC"; then
+ PKG_CHECK_MODULES(MAC, gtk-mac-integration)
+fi
+
+# Check for relative build
+AC_ARG_ENABLE(relative, [AS_HELP_STRING([--enable-relative],
+ [enable runtime search paths @<:@default=no@:>@])],
+ [DOTS=".."; ac_default_prefix="/"])
+AC_SUBST([DOTS])
+
+# Output