you could use a script that is attached to a F key
example:
Code:
menu * {
  Minimize All windows on $network : F10
  Restore All windows on $network : F11
  Minimize All windows on all networks : sF10
  Restore All windows on all networks : sF11
}
F10 {
  var %a = 1, %b = $window(*,0)
  while %a <= %b {
    window -n $qt($window(*,%a))
    inc %a
  }
}
sF10 scon -at1 F10
F11 {
  var %a = 1, %b = $window(*,0)
  while %a <= %b {
    window -r $qt($window(*,%a))
    inc %a
  }
}
sF11 scon -at1 F11


Gave you a bit more than you actually requested, but figured most of it made common sense to have.