I have a JavaFX app running in the browser (Firefox). It doesn't seem to be able to create and show new stages (dialogs in particular). My application is signed (runs fine via Java Web start), but is there something special about the browser environment?
I withdrew this as a question, because I realized that it is working, just incredibly slowly. Popping up an Open File dialog took over 1 minute, and I interpreted that as not being able to open windows. And strangely ever since then opening File Dialog boxes has been fast. Go figure!