Until the adjustable background lighting/colouring can be implemented, the registry hack that Jim gave us some time ago is relatively simple to make, assuming you don't mind monkeying around in the registry.
However, for those who prefer the simple life
, download and run the following little script and it will do this for you...
BackgroundColor.reg
Using the function keys F1 to F4 will simply return the colours back to the current MA3 defaults.
The BackgroundBottomColor ff113111 and BackgroundTopColor ff000040 in the script can be changed to whatever you want.
But those two values give a rather nice effect, IMHO. (See below...)