Changed osgbrowser example to use a local CMakeModules/FindXUL.cmake script,

and specialization of GTK dependencies to only non Windows/OSX platforms.

examples/CMakeLists.txt

@@ -112,10 +112,11 @@ IF(DYNAMIC_OPENSCENEGRAPH)
         ADD_SUBDIRECTORY(osgpdf)
     ENDIF(POPPLER_FOUND AND CAIRO_FOUND)
     
-    IF   (XUL_FOUND AND GTKGL_FOUND)
-        ADD_SUBDIRECTORY(osgbrowser)
-    ENDIF(XUL_FOUND AND GTKGL_FOUND)
-
+    IF(XUL_FOUND)
+        IF  (WIN32 OR APPLE OR GTK_FOUND)
+            ADD_SUBDIRECTORY(osgbrowser)
+        ENDIF(WIN32 OR APPLE OR GTK_FOUND)
+    ENDIF(XUL_FOUND)
 
     IF   (BUILD_OSG_WRAPPERS)
         ADD_SUBDIRECTORY(osgintrospection)