Add titles and clean-up plotting %!demos. * scripts/plot/area.m, scripts/plot/axis.m, scripts/plot/bar.m, scripts/plot/barh.m, scripts/plot/clabel.m, scripts/plot/colorbar.m, scripts/plot/comet.m, scripts/plot/comet3.m, scripts/plot/contour.m, scripts/plot/contour3.m, scripts/plot/contourf.m, scripts/plot/cylinder.m, scripts/plot/ellipsoid.m, scripts/plot/errorbar.m, scripts/plot/ezplot.m, scripts/plot/ezplot3.m, scripts/plot/ezpolar.m, scripts/plot/feather.m, scripts/plot/fplot.m, scripts/plot/hold.m, scripts/plot/isosurface.m, scripts/plot/legend.m, scripts/plot/loglog.m, scripts/plot/loglogerr.m, scripts/plot/mesh.m, scripts/plot/meshc.m, scripts/plot/meshz.m, scripts/plot/patch.m, scripts/plot/pcolor.m, scripts/plot/pie.m, scripts/plot/pie3.m, scripts/plot/plot.m, scripts/plot/plot3.m, scripts/plot/polar.m, scripts/plot/rectangle.m, scripts/plot/ribbon.m, scripts/plot/rose.m, scripts/plot/scatter.m, scripts/plot/scatter3.m, scripts/plot/semilogx.m, scripts/plot/semilogxerr.m, scripts/plot/semilogy.m, scripts/plot/semilogyerr.m, scripts/plot/sombrero.m, scripts/plot/stem3.m, scripts/plot/surf.m, scripts/plot/surfc.m, scripts/plot/surfl.m, scripts/plot/title.m, scripts/plot/waterfall.m: Add titles and clean-up plotting %!demos.

--- a/scripts/plot/contourf.m
+++ b/scripts/plot/contourf.m
@@ -89,6 +89,7 @@
 %! colormap ('default');
 %! [x, y, z] = peaks (50);
 %! contourf (x, y, z, -7:9);
+%! title ({'contourf() plot (filled contour lines)'; 'Z = peaks()');
 
 %!demo
 %! clf;
@@ -97,4 +98,14 @@
 %! [X, Y] = pol2cart (theta, r);
 %! Z = sin (2*theta) .* (1-r);
 %! contourf (X, Y, abs (Z), 10);
+%! title ({'contourf() plot'; 'polar fcn Z = sin (2*theta) * (1-r)'});
 
+%!demo
+%! clf;
+%! colormap ('default');
+%! x = linspace (-2, 2);
+%! [x, y] = meshgrid (x);
+%! z = sqrt (x.^2 + y.^2) ./ (x.^2 + y.^2 + 1);
+%! contourf (x, y, z, [0.4, 0.4]);
+%! title ('Hole should be filled with the background color');
+