The brakeImage property defines the image file name to use for the brake bar.
If this is NOT set to no-image, it will override the color property.
The image must contain both the background and the dynamic bar image.
If the bar is drawn vertically (default), the background is taken from the left half of the image
and the dynamic bar from the right half.
If the bar is drawn horizontally, the background is taken from the upper half of the image
and the dynamic bar from the lower half.