As I said, this is because the current version of exo isn't "gio-aware/ready". So the preferred apps you set in exo won't affect gio (which is used to open the link in the plugin about dialog). This is fixed in exo 0.5, currently in development, so this will be fixed when Xfce 4.8 is released (not for lucid).
As I said, this is because the current version of exo isn't "gio-aware/ready". So the preferred apps you set in exo won't affect gio (which is used to open the link in the plugin about dialog). This is fixed in exo 0.5, currently in development, so this will be fixed when Xfce 4.8 is released (not for lucid).