Note: If you are using JavaFX 8 you may want to check out the (official) official JavaFX Dialogs! This is the reason why this project will not be actively developed further and will only work for JavaFX 2.
Oracle has opened up the JavaFX UI Sandbox repository on OpenJFX as announced on the fxExperience blog. Controls in the OpenJFX repository might eventually be included in a next JavaFX release.
This GitHub project provides simple jar files for some of those sandbox controls.
JavaFX Dialogs are simple dialogs in the style of JOptionPane from Swing.
Details about JavaFX Dialogs
Marco Jakob (http://edu.makery.ch)