Unity Scale (Super + W) flips windows around when Xchat is the foreground application

[Andy Pennebaker]

I like using Unity Scale (like Mac OS X Expose) to quickly get to different windows. For the most part, Unity Scale works well. However, when I'm using Xchat in the foreground and another application such as Terminal or Firefox in the background, activating Scale with Super+W, Scale strangely shows the windows out of order in the Scale overview, forming a mirror image.

Repeatedly pressing Super+W in Scale continues to rapidly flip the window previews to the correct order and back, creating a disorienting effect.

Using Xchat 2.8.8 on Ubuntu 14.04.