FVWM: Style ... SkipMapping

Greetings,

maybe I totally misinterpret the "fvwm" manpage ...

1. What I want:
   During the login process on my laptop I want to fire up Firefox using
   a page different  from the  default page  where my terminal window is
   opened.   This way  I can start  entering commands  without having to
   wait for Firefox loading all its tabs.

2. What I do:

   $ grep -C2 Firefox ~/.fvwm/config
   # Always position a "firefox" window on page "0 0 1":

   Style Firefox      FixedPPosition
   Style Firefox      PositionPlacement 0p $[_WINDOW_TOP_]p
   Style Firefox      StartsOnPage 0 0 1

   #
   $ grep -iC2 firefox firefox-start-up.sh
   # Finally start "firefox" in its own page without going there:

   FvwmCommand 'Style Firefox SkipMapping'
   nohup firefox > /dev/null 2>&1 &

3. What happens:
   Firefox is starting  in its own page,  but this page  is also the one
   shown on the screen rather than the page containing my terminal wind-
   ow.

4. Technical information:

   Gentoo, package x11-wm/fvwm, version 2.6.5-r3.

Cann anybody tell me what I have to do differently?

Sincerely,
  Rainer