The ModuleSynchronous command is very similar to Module. Fvwm stops processing any commands and user input until the module sends a string beginning with "NOP FINISHED STARTUP" back to fvwm. If the optional Timeout is given fvwm gives up if the module sent no input back to fvwm for secs seconds. If the Expect option is given, fvwm waits for the given string instead. ModuleSynchronous should only be used during fvwm startup to enforce the order in which modules are started. This command is intended for use with the (currently hypothetical) module that should be in place before other modules are started.

Warning: It is quite easy to hang fvwm with this command, even if a timeout is given. Be extra careful choosing the string to wait for. Although all modules in the fvwm distribution send back the "NOP FINISHED STARTUP" string once they have properly started up, this may not be the case for third party modules. Moreover, you can try to escape from a locked ModuleSynchronous command by using the key sequence Ctrl-Alt-Escape (see the EscapeFunc).