From KDE UserBase Wiki

    Plasma 4 plasmoid issues

    Icon-only Task Manager

    2015: Context menu entries to Unlock and lock Launchers are not present when right-clicking on a launcher. You have to find an empty space on the task manager.

    2015-08: install unsigned packages

    This message box appeared at desktop startup without any apparent reason:

    "Plasma shell

    You are about to install unsigned packages that can compromise your system, as it is impossible to verify if the software came from a trusted source. "

    I wonder if this is something to worry about.

    (Not reported yet, wait for Plasma 5)