A DESCRIPTION OF THE REQUEST :
Actually when we're typing a Persian or Arabic text on the textual components like textfield on the JavaFx platform and even Swing, there is a little space (maybe 1 pixel) between Persian and Arabic (RTL) letters, it behaves like "letter-spacing" property on the CSS, for a quick test you can use below Persian text, you can size up this text if you need more details:

یک نمونه متن فارسی

JUSTIFICATION :
Nowadays Java and JavaFx are popular in Iran country because designing and developing enterprise and free softwares in Iran is increasing very fast so we need to a good platform like Java for making multi platform softwares and apps and in fact good RTL text rendering for all components.