Hi Erel,
This is the computer used for development, with B4J installed. I've decided a few days ago to upgrade it to Windows 10 just to be at the latest version for testing purpose.
The application is very simple, the interface is designed with Java FX builder 2.0
The same thing happen when I run the application directly from B4j. I have seen that if I'm using only the keyboard, everything seems to be ok.
The problem appears only when I click with the mouse on a dropdown box which does not have the focus.
Other java apps (jar files) with combo boxes seems not to have this issue.
I do not exclude an issue with my particular system. I will test it again later in the evening on another Windows 10 computer with B4J installed.
Thank you,
Dan