Track spacers

New mockup: Different sized spacers. Different shades. It should be user-customizable (size+shade) to suit everyone's tastes. (wouldn't that rock for the TCP as well?) reminder... this FR is in the tracker for voting:

Evan, I see what you're trying to achieve, but the VAST majority of users are more interested in seeing colours and gradients to achieve their desired goals. I look at that window and I think to myself "Why not just leave a blank track?" which would be easier manage, and requires no additional programming. You could add in "empty items" to help you identify where you are up to as well.