panel background colour error in geom_tri_tern

[Joey O Brien]

Hi Neil, many thanks for your great package it is extremely useful. One small point, I believe that when one applies geom_tri_tern to a plot there is no option to change the colour of the panel background (i.e., tern.panel.background in the theme_custom option makes no change), looking through the source code I’ve noticed you use ‘gray50’ as a default in GeomTriTern.

Is it possible in anyway to change a panel colour when it has no occurrence in any bin?