tf.fgd help

OK I've edited my tf.fgd file so that the hoodoo, bloodstained and halfacre textures show up but every time I restart the sdk launcher the fgd file is re-written back to it's defaults, thus hiding those textures again.

Does anyone have any idea why this is happening and how I can stop it please?

Thank you sir. I didn't realise there was a fix for this already posted.