TkGS is a project to replace XLEL to improve Tk's performance and cross-platform (or "device-independent", more properly) "maintainability". These enhancements might open up such new possibilities as a framebuffer-targeted Tk, themes support, graphical refinements including alpha transparency, ...
What is the status of TkGS -- it looks like a wonderful idea, but I'm wondering if it is stuck... Nothing seems to have happened for a long time...