The internet is full of conflicting information about this subject, and 4.3 hasn't even officially released yet so it's all old anyway... I gotta come here to the source.
Alright folks, so say I have a TileMapLayer called Ground that has 9 grass tiles on it in a 3x3 square. The navigation is set up to make the entire tile traversable, and there's no collision on it.
Then I have a TileMapLayer called TheTree which has one tree placed in the center of the square. The navigation is set up to make the area where the trunk is non-traversable.
If I add a NavigationRegion2D to the scene and draw a box around my TileMapLayers, I expect the navmesh that's generated when I click the bake button to be a 3x3 square with a little hole cut out in the middle.
That doesn't seem to be the case. How do I do what I want to do here?