y = halfDown(g.toDomYCoord(yGridlines[i], 0));
// Step through the pixels of the line and test the pattern.
for (x = halfUp(g.plotter_.area.x); x < g.plotter_.area.w; x++) {
y = halfDown(g.toDomYCoord(yGridlines[i], 0));
// Step through the pixels of the line and test the pattern.
for (x = halfUp(g.plotter_.area.x); x < g.plotter_.area.w; x++) {