You can follow the process of filling passages:
1) Draw the passage on Layer 2.
2) Select swamp or open water, then click into the fill area.
3) Cut the filling and paste it onto Layer 3.
4) Select the background color, then click into the fill area.
5) Cut the background filling and paste it onto Layer 4.
6) Draw stones and symbols on Layer 1
7) Display Layers 1, 2, 3, and 4 together.
[[File:Layers.PNG|none|auto]]