From https://openjfx.dev.java.net/:
- "a lightweight tool that allows you to interactively create graphical elements using the JavaFX Script programming language. It consists of a code editor and a canvas. Whatever you type into the code editor will be displayed in the canvas. It also demonstrates the benefits of JavaFX Script being a statically-typed programming language, providing code-completion and as-you-type validation, in addition to syntax highlighting."
Run JavaFXPad: http://download.java.net/general/openjfx/demos/javafxpad.jnlp