Can someone explain the following effect to me? I have a simple picture in xfig with black lines and only one layer. I export the figure as metapost, run mpost and rename the extension to mps. Then the figure is included in the TeX-file with includegraphics. This way I get black lines in my dvi-viewer and white lines after postprocessing with ppower4 (white is also the color I use for text). This fine, although I don't understand why.
Now, if I introduce more layers (in order to cover some parts of the picture with the background color) the color of the lines after postprocessing changes from white to black, but sometimes only in some layers. I'm lost and can't determine what the displayed colors actually depend on. The setup is basically that from leveldemo.tex. Thank you, Nils Rosehr
