I'm trying to show the transfer function on a volume render.  Plotting a velocity component, I set the transfer function with 4 Gaussians all with the same width.  The range of the transfer function is -1.e7 to 1.e7, but for some reason, when output, the upper label in the colorbar is not 1.e7 but a bit lower (9.92e6).  I am not sure where the code is that draws this, and I am confused why it is not setting the tick at 1.e7. It gets the bottom tick right.