How do I recolor the selector graphic in the editors?

[Garth's Equipment Shop]

I made a new custom palette for some new tiles sets I created and imported and I changed the text colors to fit with the new palette. But somewhere along the way I lost the selector graphic. I can still select things but it is difficult since I cannot see what is selected. I know I can change the background by changing the background color for text color 0. But what if I just want to change the selector box color?

EDIT: Got a response from Chris on Facebook :)

Chris Hopkins
That might be color 15? I think there's a loose assumption that colors 0-15 stay "standard".