How do I hide or show a map layer?
The visibility of layers can toggled with slice commands. Each map layer is actually a slice, and the normal commands for hiding them work (even map layer 0). For example, to hide the 2nd layer (layer 1):
plotscript, hide layer 1, begin variable(sl) sl := lookup slice(sl: map layer 1) set slice visible(sl, false) end
To show it again:
plotscript, show layer 1, begin variable(sl) sl := lookup slice(sl: map layer 1) set slice visible(sl, true) end
In the map editor
Layers can be hidden in-game by disabling them in the map editor.
Go to the "Layers and Tilesets" menu (or press CTRL+L while placing tiles) and press Enter on one of the lines that says "Enabled (<-Visible in editor->)" to enable/disable the layer. You can't disable layer 0 in this way.