change paper color to opaque

Does anyone know if there is a way to change the paper color (the background behind text) to opaque so a photo behind would show?

In the Appearance tab of Tools > Options, choose Full Screen > Page from the Colors list and double-click on the colour block to change it. Set the Alpha channel to 0 to make the paper colour completely transparent, so the backdrop image will show, or choose some value between 0 and 255 to make it semi-transparent.