Hi there again!
This time I won't show a new tool, but a new feature for our good old Level Editor: Decals. These are used mainly to add nice details to the level without much sweat. Here is a little video demonstrating how these can be used (to create a nasty mess for example :) )
Nice to know I'm not cleaning that
As you can see, there is some stuff to be tweaked and optimized, but I tell you it's still cool to use :D