You need to use one of the selection techniques described in the editing chapter in the manual to select just the fill and not the outline. I prefer to first select both entities by clicking on the edge, then combining it with NOT Color 0 to remove the outline from the selection, but you can also use list on the entities and find their entity tags, and then do a select by entity tag to just pick the fill.

This is cool. Not sure if it actually qualifies as a map (not that it has to), but it is a great illustration.

Yea, this feature is primarily intended for things like dungeons, buildings and (star)ships.

Sounds like a great way to utilize the otherwise wasted time in meetings.

Great work so far.

I've written a blog post with explains the RGB Matrix effect in more detail.