Light color line on dark theme

I’m on Fedora + Gnome 3. I’m using the system dark theme. So Valentina set up dark theme too (which is a great dark theme).

When I draw a point or a line, it is draw in black on a dark grey background.

It is not convenient for me to see my work. So I have to change the color, line by line, each time I am drawing…

I have not find a way to change the default color.

So is it possible to either change the default color of lines/points to a gray/white one when dark system theme active, or add the possibility to let me set up a default color ?

Thanks for the great job !