EXPERIMENTAL (details may change in a future release version)
2D plots: colorbar labels are placed at the palette coordinate used by the
plot for variable coloring "lc palette z".
3D plots: colorbar labels are placed at the z coordinate of the point.
Note that in the case of a 3D heat map with variable color that does not
match z, this is probably not the correct label.
See also plot using xticlabels (p. ).