there have been some discussions on the beta list about this:

the next implementation will be:
components in dark gray and hard contours in black. it will be almost not visible when there are only components but when ever there is a mix of contours and components it clear.

if you have other ideas you could send me your configuration (use inside DrawBot)

from defcon import Font
from fontTools.pens.cocoaPen import CocoaPen

# set a path
path = u"path/to/my/Font-Regular.ufo"

# get the font
font = Font(path)
# get a glyph both with a contour as with a component
glyph = font["tcaron"]

# background fill (same color as the window)
fill(237/255)
# draw rect with the size of the canvas
rect(0, 0, width(), height())

translate(100, 100)
scale(.8)


# fill with black
fill(0)

# get a pen
pen = CocoaPen(font)
# draw the glyph in the pen
glyph.draw(pen)
# draw the pen.path 
drawPath(pen.path)

# new pen
componentPen = CocoaPen(font)

# draw only the components in that pen
for component in glyph.components:
    component.draw(componentPen)
    
# set a fill
# component fill color
# 50% black with a 30% alpha value
fill(.5, .5)
#stroke(1)
# draw the compontens path
drawPath(componentPen.path)