Sudden Change In Arranger Outline Colour

I was just messing about trying to create a theme for myself and discovered the above
Adjusting the value of body_back and r/g/b slider by one in these examples provokes a sudden change in the outline of patterns listed to it’s left.

I’m sure I read another thread about something similar but couldn’t find it in the bugs section.

Thats the Renoise “magically make sure that the grid is always visible technique” ™.

Its done on purpose, to avoid that you have to specify a custom color for the grid.

Ahh I see, I thought that was a possibility - 'tis clever though! :)