WindowBlinds 6 "Explorer Background" Display PROBLEM

Just wondering why the opaque/transparent explorer background option only works with windows that have the "preview pane" option disabled/turned off?  It works beautifully on windows with this off, but as soon as you enable the "preview pane" the background goes black or a dark shade of gray, depending on how far left you have the opacity slider set in the WB config.  It would be nice to get this bug fixed as i like to have the preview pane of Vista turned on, and cannot if i want the see thru explorer backgrounds.  Please see attached screenshot.  As you can clearly see the one window with NO preview pane shows the opaque background as it should.  However as soon as you enable the preview pane, things go black.  Why and can this issue be addressed.