Is there a way to display Compiled Help manual CHM in a javaFX app, without using java.awt.Desktop from AWT ?
Calling A CHM reader using Runtime.getRuntime().exec(help.chm) is an option, but to make it cross platform, this would require every user in mac, win and linux to have a CHM reader installed.
What's the best option for a cross platform solution ? should I extract it to HTML and display it in javafx.scene.web.WebView ?
Given your wish to be platform independent, I'd advise to go to the HTML route as you yourself suggested. I don't know your reason for converting CHM to HTML if you also control the source, in that case I'd either use HTML directly or markdown to HTML.