Flash and Java applets running inside of npviewer.bin are cause SELinux access denials, causing the applets to fail to function properly. For example, the Flash image uploader for Facebook fails to work. (Using proprietary Flash plugin.) The usual denied message is this one: type=AVC msg=audit(1207708459.489:321): avc: denied { execmem } for pid=28566 comm="npviewer.bin" scontext=unconfined_u:unconfined_r:nsplugin_t:s0-s0:c0.c1023 tcontext=unconfined_u:unconfined_r:nsplugin_t:s0-s0:c0.c1023 tclass=process execmem may be icky, but npviewer.bin needs it in order to actually properly run the (essentially) two programs it was written for.
You can setsebool allow_ns_plugin_execmem=1
Why should that be necessary? If you know that the common use for npviewer requires it to be on, turn it on by default.