This past year I have done some major work refactoring the code for this editor and adding control forms for each layer to give a wide range of options and processes for creation.
The forest Layer of this editor now contains components to select forest textures from a library by forest regions (such as Boreal Forest, Dry Rocky Mountains, Coast Mountains) Each texture set contains various textures containing different tree mixes at various densities. With this control it allows for more accurate representational forest creation of various regions.
The Forest Editor also contains controls for procedural generation based on terrain elevation and slope aspect. (These are generally the main factors determining forest types)
There are still controls for specific texture assignments, forest growth value modification and texture randomization to allow for detailed editing of forests for the scene.
Bellow is a video demonstrating most of the forest editing controls I have implemented. First is using the detailed texture controls for editing terrain and forest textures, as well as the texture selector. Second this video shows procedural forest generation and its functionality by modifying various parameters.