If this method is implemented, a "Show All Help Topics" item will appear in the menu and this method is called when the user selects it.
Original signature is '- (void)showAllHelpTopicsForSearchString:(NSString *)searchString'
Available in Mac OS X v10.6 and later.
- searchString (NSString)
- The search string.
- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later)