I have just finished my first repaint of the 777 however I had a bit of trouble with having solid windows. I am not a noobie at repaints even with PMDG paint kits and found that the window alpha channel was not present. A bit of masking round the windows and black paint solved the problem but I was just wondering if anybody else had found this.

You don't even need to use a mask, just take the alpha from your base textures and modify it to suit your livery, much faster imo.