When the user presses a mouse button upon an object fvwm waits to see if the action is a click or a drag. If the mouse moves by more than pixels pixels it is assumed to be a drag.

Previous versions of fvwm hardwired pixels to 3, which is now the default value. If pixels is negative or omitted the default value (which might be increased when 16000x9000 pixel displays become affordable) is restored.