I ran across this Oracle white paper:
It appears that the Listener can only use XSLT 1.0 but printing charts seems to be part of XSLT 2.0
I'm still new to the area of making custom PDF reports. (I haven't gotten one to work, yet.)
Too bad Oracle doesn't have a limited run-time edition of BI Publisher for APEX.
Thank for your replies Mike and Tony,
Mike, I'm aware of that white paper, it's very informative.
Tony, I wasn't aware of that right mouse action, that can be usefull. Unfortunately, in my case users can use a browser of their own liking, so flash support is not guaranteed. That can become a problem.