I've finished working on the Layers Window for now for Curver. I have to say: switching to Sciter so far has been a huge step forward from pure win32. The window is functional, including drag and drop, in about 160 lines of simple html and script code. I know line count is not an accurate measure of anything, but considering that the win32 custom tree control I was creating in parallel with the layers window in Curver before the switch was ~1400 lines of code, and it's not finished, the difference to me is huge. Picking the right tools is crucial when you're a lone developer hoping to finish a project in a reasonable time.
Stay tuned for more updates soon.