FVWM: rare behavour with mouse buttons

Hello

I have used fvwm since around pre 1.00 kernels and have had a
minor problem since the last release, which is extremely rare,
and corrects itself within a few minutes, how or why I don't know
so I am merely reporting something in case someone is interested.
It is as follows:

I have 3 buttons in the upper right hand corner that perform the
following functions depending on which mouse buttons are pushed.

   1. iconize
   2. expand full width of the screen
   3. expand full height of the screen

Which are implemented by

  Mouse 1 2 N        Maximize true 0  33
  Mouse 3 2 N        Maximize true 0  100

  Mouse 1 4 N        Maximize true 27  0
  Mouse 3 4 N        Maximize true 100 0

  Mouse 0 6       A       Iconify

Now what happens is that these mouse clicks totally stop working.
No response whatever. A few minutes later everything is okay.

Bruce