Illustrator: How do you change default Fill/Stroke Colors for the 'D' key?

Pressing D will switch to the default Fill/Stroke colors (which is White Fill / Black Stroke in Illustrator).

I remember having read about a way to define your own default Fill/Stroke colors, but I forgot how – e.g. say I want Transparent Fill and Black Stroke.

Answer

Ok, the answer was easy (but hard to recall if you've forgotten it like me):

1. Set your preferred Fill & Stroke.



2. Open the Graphic Styles panel; Window > Graphic Styles.


3. Click the New Graphic Style button.


4. Hold Alt/Opt key and drag the new style onto the default style. (The default style is the one having a miniature Fill/Stroke symbol in the lower left corner).

Now, pressing 'D' will change all selected objects to the new default style.

A bonus tip: In the Graphic Styles panel, open the Graphic Styles Libraries Menu and choose for example Additive. While having a path selected, Alt-/Opt-click on one of the Additive styles, to add some very interesting effects on your path.