I've been re-working the filters UI. I added a DropDownList option type to allow selecting from a list of options. To demonstrate it, the Generate Noise Heightmap and Generate Noise Blend Layer filters were added (replacing some earlier filters). The new filters use a drop-down list to select a noise function type for generating a heightmap or a blend layer, respectively.
Image of the filter drop-down selection:http://i.imgur.com/XchuPU4.jpg
I implemented some performance fixes to speed up the process of generating a heightmap or blend layer map from a noise kernel, eliminating some redundancy and taking advantage of the ANL option USETHREAD in order to use multi-threading during kernel mapping.
I'm still working on how I want to handle file handling: save, load, new. Common sense would dictate that I implement a project structure of sorts, and encapsulate all of the various data (heightmap, blend maps, brush settings, material settings, etc...), so I'm working on a design for that. Also working on designs for the tool bar, and a rework of the brush dialog and the terrain layer selection dialog. (Man, I hate UI development. Hate it.)