Earlier the subject of how to draw ticks and grids for image data was
brought up. The problem was that images obscure the ticks. This can
be fixed by drawing the ticks after the rest of the axes. The
question I am considering now is whether the grids should also be
drawn last. This applies to image and non image axes. If, on a line
plot or bar plot, should the grids be in front of or behind your data?
Another possibility would be to put the grids in front with a semi
transparent alpha, so you could see your data through them. Of
course, on backends like postscript which don't have an alpha channel,
this wouldn't work.