If I execute the script, (copy and paste source from web page into a file and execute the file with .x) I get only the black contour lines (see c2a.png). After clicking somewhere in the middle of the canvas with the middle mouse button, the images changes to something else but the result is still not the desired one.
Is the example broken, or is this a “feature” of my root installation (ROOT 5.20).
Cheers, J.
Thanks for having a look at this. Your quick workaround works fine for me.
Although not being a major problem, the “middle-mouse-button-feature” still remains. So probably I tipped over two independent problems in ROOT. However not middle clicking on a canvas doesn’t seem to be too hard for me, so I’m fine with the workaround above.