I'd like the ability to specify a custom textured paint (e.g. a linen paper, slate rock or sandstone texture) as the base for the whole UI or some controls so that the the UI can easily be nicely textured in addition to being color coordinated (similar to textures available on a laminated or tiled floor).

As a background, caspian.css defines the following setting:

   /* A light grey that is the base color for objects. */
  -fx-base: #d0d0d0;

This is great because, by overriding just one setting in your custom css, you can get a totally different themed color for your application. Applying a custom textured paint here, and having the default css adapt so that everything still looks good, is the kind of thing I'm requesting. Optional use of a bump mapped effect may also be considered.