I'm using Xfce 4.10 which I compiled and configured for Porteus Linux (Slackware 13.37 base).  I'm trying to improve the aesthetics a bit and would like to use an image background for the panel (once I find one that I like...).  However, when I select a long, narrow image like this:

Some of the buttons (such as actions menu, clipboard and clock) don't display the image properly. Instead of having one long image across the whole panel, the image starts over again wherever these buttons are placed.  I've enlarged my panel and moved the buttons around to show what I mean:

It might be hard to tell at first glance, but the actions menu ("guest") has a break in color (where the image starts over again, it's repeating the same colors from the far left of the image), as does the notification area, xkb-switcher, and clipboard.

I've searched the forum and looked through the bug page for the panel, and don't see bugs posted about this.  Am I missing a configuration option somewhere?  Has anyone else experienced this?

Thanks!