Visualise layer or connection

Wouldn’t it be good to easily see which layer you are working in in your IDE?  When working in a multi layer environment one often has a class named Customer in every layer which makes for some document switching before finding the right one.  Add an icon in a corner or a slightly tinted background.

When working with multiple databases at once in a query tool it is often a hassle to keep the windows of the different databases apart.  Often one has two servers QA and Production with identical (or similar) database names.  It is very important to not update the wrong one.
Couldn’t one have a slightly tinted background that shows where one is?

Update:
There is an extension that can colour the tabs but it doesn’t give the full visual  clue I am looking for.