This is about Lubuntu 15.04 vivid which is a system upgrade from 14.10
I have a problem adding news apps to the application launch bar because the new apps don't show.
I installed apps like VLC player, Skype, Chromium etc. I want to add these apps to the application launch bar. Going to add/remove panel items, then click application launch bar and preferences. The small file manager window shows up with left the launchers and right the installed applications. So far all good. However, none of newly installed apps is showing on the right. So I can not add them to the application launch bar. The new apps do show in the normal menu and they work fine but that doesn't matter or help for this issue.
As I just discovered, the same happens if I want to set a default application for opening a file, e.g. VLC to open a MP4 video file.