Hi Psysoul,

From the processing sources, it seems that the leading is a float value which is equal to 14 by default (while font size default is 12). Whenever you change the font size the leading is set automatically by the formula:

   textLeading = (textAscent() + textDescent()) * 1.275f;

You can also access this value using g.textLeading (g being the reference to PApplet's PGraphics object).
For example,

1. println(g.textLeading);
2. PFont font = createFont("Arial", 28);
3. textFont(font);
4. println(g.textLeading);