Split Editor - indicate which tab is active?

If I split my editor into multiple tab groups, is there any way to configure things so that the active one is highlighted (or otherwise visually designated) in some way?  Notice that in the following, other than the cursor, there's no way to tell which of the three windows is active:

One idea (but by no means the only one) is to grey out the other windows.  Something like this:

Is there any way to do something like this?