I'm not sure what version C Elston used when requesting the above, but I'm on 1.2.3 and for me it's super clear difference between the panes. In fact, the non-active one is rendered with a quite intrusive blue background. I'd like to request that the difference between the panes is visible, but a lot more subtle.

Not sure if it's relevant, but I'm using the theme Clearlooks, with nothing tweaked.