handle_open_for_backup
Description:
public virtual signal bool handle_open_for_backup (DBusMethodInvocation invocation, UnixFDList? fd_list, Variant arg_options)
  
  Signal emitted when a remote caller is invoking the OpenForBackup D-Bus method.
If a signal handler returns true, it means the signal handler will handle the invocation (e.g. take a reference to 
        invocation and eventually call complete_open_for_backup
       or e.g. return_error on it) and no order signal handlers
      will run. If no signal handler handles the invocation, the 
        UNKNOWN_METHOD error is returned.
Parameters:
| invocation | |
| fd_list | 
           A UnixFDList or   | 
      
| arg_options | 
           Argument passed by remote caller.  | 
      
Returns:
| 
           
  |