In Blender 2.78a, you can change the color of the grease pencil, but the drawn lines remain black while you are drawing, and only become the desired color once the mouse is released.
gp_layer.tint_color = Vector([0,1,0]) gp_layer.tint_factor = 1.0
This is different from the behavior in previous versions, eg 2.77a, when the markings were drawn in the desired color. (I am drawing on top of noisy greyscale images, so it's difficult to draw accurately when the markings are black.)
How can the color of the grease pencil be changed to also affect the color while actively drawing?
UPDATE with Python solution (thanks to Timaroberts tip below):
for gp in bpy.data.grease_pencil: for plt in gp.palettes: # color of stroke while drawing plt.colors.color = Vector([0,1,0]) for lyr in gp.layers: # color of curve once drawing is completed lyr.tint_color = Vector([0,1,0]) lyr.tint_factor = 1.0