The list of window managers that the config module offers for using.
The format is normal .desktop files:

Name - required, name to display in the configuration dialog.

Exec - required, the command to execute to launch the window manager.
    If launching fails for any reason, it must quit with non-zero exit
    value and not do anything else (show an error dialog, try to run
    a fallback, etc.).
    
TryExec - optional.

X-KDE-WindowManagerTestExec - optional, a command that will be run and if
    the exit code is not 0, the window manager won't be used (can be used
    e.g. to detect that a window manager which requires compositing support
    cannot be run on systems without such support).

X-KDE-WindowManagerId - optional, the name under which the window manager
    registers with the session manager (if different from the name
    of the .desktop file)

X-KDE-WindowManagerConfigure - optional, the command to run to configure
    the window manager

X-KDE-WindowManagerRestartArgument - optional, the argument to pass
    to the window manager to restart it directly in the running KDE
    session; if not present, KDE restart is required (which is generally
    a good idea anyway, but this can be useful for e.g. checking)

X-KDE-WindowManagerConfigureParentArgument - option, if present, this
    argument and the X window id of the configuration dialog will be passed
    to the configuration command (e.g. '--parent 13254543'). The configuration
    tool may specify this window as the parent of its window.
