Wouldn’t it be interesting to have a negative space in which to draw?
By that I mean drawing on a black background
The preview pane at the bottom of the screen can be reversed with the little white/black circle button. You’re not literally drawing in the black but you can see the effects of your drawing reversed out.
Yes, I know but I am wondering if it would be interesting to actually draw on a black background.
You can set the background color to black in preferences or assign a Master Color (custom parameter in Font Info > Masters).
I’m spacing and kerning a type for negative use.
Is the only way to make the drawing/kerning space negative by altering the colours in Prefs?
It would be useful to be able to toggle this via a shortcut so if I want to correct oultines I don’t have to keep changing the Prefs
Tried Dark Mode?
I’m not keen on Dark Mode – my Goth days are long gone 
Besides it doesn’t change the draw space, this remains black on white
Run this in the macro window:
Glyphs.defaults["GSEditViewDarkMode"] = True