popup.js is broke in horde-3.0.10 and fixed in 3.0.11. I have patched the 3.0.10 RPM for 3.0.11, just waiting for it to be officially made and released for testing. I also don't want to unofficially release it yet, until I have had a chance to test it and all of the other horde related updates I have created with what I have currently available on my contribs site.
So, for the short term, download horde 3.1.x tar file and use the popup.js from there. It works as well. Just make sure to change the permissions and ownership appropriately.
Hopefully sometime this week I can get around to the testing so I can release the newer rpms.
JB