FVWM: how to prevent involuntary page switching?

Hi,

how can I prevent fvwm from automatically switching to the desktop page
where an application like gajim receives a message and activates a
window (or whatever it does to force this switch)?

As you can imagine, it´s very annoying when you´re suddenly switched to
a different program residing on a different page, especially while
you´re typing somewhere else.