Focus and Selection - Archive of obsolete content
you can do this anywhere you have a xul browser document by simply: document.commanddispatcher.advancefocus(); in fact, the commanddispatcher simply implements the nsidomxulcommanddispatcher interface.

nsIControllers
tcontrollercount(); nsicontroller getcontrollerforcommand(in string command); unsigned long getcontrollerid(in nsicontroller controller); void insertcontrollerat(in unsigned long index, in nsicontroller controller); void removecontroller(in nsicontroller controller); nsicontroller removecontrollerat(in unsigned long index); attributes attribute type description commanddispatcher nsidomxulcommanddispatcher obsolete since gecko 1.9 methods appendcontroller() adds a controller to the end of the list.