If you try to add a color etc to the Line POP as an attribute it doesn’t let you set the color, the default values stay greyed out and read only. I’d expect it to work like the attribute POP does.
Hello @Ennui
I’m opening a bug for this. Thanks.
I think it’s a feature 
(default for Color is vec4(1)), Create POP is the same, but yeah we could allow to override it.
You can still set each point color individually on points page.
Conceptually it’s a bit different from Attribute POP which sets a value, and default for Color is still vec4(1) here (which you can see if you set Color to only a group of points)
But it never seems to allow you to change them so why would they be there in that case or did I miss something?
They’re just sitting there dark grey and taunting me!
You can set the default for Custom attributes, that’s when it’s not greyed out.
In any case, point taken, we’ll allow to set defaults for all attributes in Line/Create