Just wanted to post this here for everyone's benefit (and hopefully less spam in the bugreport).

In comment #143, Edward posted a workaround which works for me as well as others. However, I have an alternative workaround which doesn't involve creating files that the package manager won't know about (bad thing):

Edit /usr/lib/nspluginwrapper/i386/linux/npviewer to include a line, "export GDK_NATIVE_WINDOWS=1".

Step-by-step instructions:

1) Run "gksudo gedit /usr/lib/nspluginwrapper/i386/linux/npviewer" with Alt-F2.
2) Add the "export GDK_NATIVE_WINDOWS=1" immediately before the last line of text.
3) Save and exit.

You should then be golden! Please post here if it doesn't work. Also, please remember to revert the npviewer script to its original state when next upgrading your system.

For reference, my npviewer script looks like:

Code:
#!/bin/sh
TARGET_OS=linux
TARGET_ARCH=i386

# dgt 02 Nov 2009
export GDK_NATIVE_WINDOWS=1

. /usr/lib/nspluginwrapper/noarch/npviewer