I'm not 100% certain that this bug isn't on my end.
I'm making theme for Windows 7 with new wsb beta and i noticed this small bug.
When i apply theme WSB command bar background use image from Toolbars, Headers, & Rebar > Rebar > Media > Background as it's should.
But when i open theme in WSB and hit test, then it use image from Toolbars, Headers, & Rebar > Rebar > Communications > Background
BTW i started this theme from scratch (start new visual style) and i use shellstyle from default Aero theme. OS is Windows 7 Pro if that matters.