Simplelist were fixed in 1.60.1. I just tried one inside a <highlights> and it works with fop. Are you sure you are getting 1.60.1?
Yes, absolutely:
java -classpath $CLASSPATH:/usr/share/java/saxon.jar:/usr/share/java/saxon-fop.jar:
/KM/usr/ziegler/DocBook/docbook-xsl-1.60.1/extensions/saxon644.jar com.icl.saxon.StyleSheet -t -o pdf/LEDATutorium.fo LEDATutorium.xml pdfsheet.xsl
You are getting two pictures from only one imageobject?
Yes.
That's odd. Can you peek in the fo output to see if it is repeated in there (which makes it a stylesheet bug)?
Oh, this was the first time I had a look into an fo-file, but I found that you are right: all graphics are only included *once*
<fo:external-graphic src="url(Pictures/Stack.png)" width="auto" height="auto" content-width="auto" content-height="auto" text-align="center"/>
Nevertheless, picture "Stack.png" appears twice on the corresp. PDF page. I've searched for the string "Stack.png" in the whole fo-document and it appears only once in the document (in the element above), but the picture can be seen twice, one below the other!
I can send you the page in PDF if you want to have a look at it.
Greetings, Joachim
