This command is useful only for an ewmh compliant pager or taskbar (as kpager or kicker taskbar) and not for fvwm modules ( FvwmPager or FvwmIconMan). It causes a compliant application to consider at least num desktops (desktop 0 to desktop num-1). The optional argument max causes a compliant application to never consider more than max desktops. If max is 0 (the default) there is no limitation. The actual number of desktops is determined dynamically. It is at least num, but it can be d if there is a window on desktop d-1 (or if the current desktop is desktop d-1) and d is less or equal to max or max is null. Moreover, a compliant pager can ask to change num itself. This is accepted by fvwm only if this number is less than or equal to max or if max is null. Note that negative desktops are not supported by the ewmh specification. The default is 4 0.