Note: version 4.6.x not 4.4.x
I have verified this bug reported at the Gentoo bugzilla http://bugs.gentoo.org/show_bug.cgi?id=278047 and the code to fix the xfprint4-manager so it will show installed print queues.
I downloaded the source code from both Gentoo and the xfce4 repository. Found them to be identical. Therefore, this bug is not limited to Gentoo.
After editing the main.c in ~/xfprint-4.6.1/xfprint-manager according to the report in the Gentoo bugzilla, xfprint configures, compiles, and installs without error.
Upon running xfprint4-manager from the shell, the error "(xfprint4-manager:3513): WARNING **: Unable to load printing system module cups_plugin.so" is displayed, but seems to works OK anyway.
Easy fix. I'm willing to test.
My 3k ~/xfprint-4.6.1/xfprint-manager/main.c is attached.
Created attachment 2744
xfprint-manager/main.c with described changes
To get rid of the warning message just remove the trailing semicolon on line 74 (after if (ps == NULL))
Product EOL (End-of-life)