I'm interested in doing the same as JavaFX does but using another language. I want to crate a simple interface on a system without X server installed.
(I know that doing anything meaningful with it will be a pain)
JavaFX runs on linux systems by utilizing the frame buffer. It captures all input and output and directly draws on the screen using the GPU. This is why there are no window frames, close button etc. JavaFX applications will run even if no X server is available because they don't really need it. I have successfully run javafx apps in terminal environment. There are libraries which give you access to a framebuffer and send commands to it but you have to check for your programming language.