@Override
                public void onAction(String name, boolean isPressed, float tpf) {
                    if (actionName.equals(name) && isPressed) {
                        // reloading the material
                        binding.reload();
                    }
                }
Will reload the spatial's materials whenever the shader file is changed
on the hard drive
@param shaderName the shader name (relative path to the asset folder or 
to a registered asset path)
@param spat the spatial to reload
jme3-core/src/main/java/com/jme3/util/MaterialDebugAppState.java