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    2.4 Managing the Output Buffer
      
     
    
      Most CLX functions cause output requests to be generated to an X 
      server. Output requests are not transmitted immediately but instead are 
      stored in an output buffer for the appropriate display. Requests 
      in the output buffer are typically sent only when the buffer is filled. 
      Alternatively, buffered requests can be sent prior to processing an 
      event in the input event queue (see paragraph 12.3, Processing Events). 
      In either case, CLX sends the output buffer automatically without 
      explicit instructions from the client application.
    
      However, in some cases, explicit control over the output buffer is 
      needed, typically to ensure that the X server is in a consistent state 
      before proceeding further. The 
      display-force-output and 
      display-finish-output functions allow a client program to 
      synchronize with buffered output requests.
    
      
      
      
        
          | display-after-function | display | Function | 
      
        
          |  | 
              
                display
              
                A display 
                object.
             
              Returns and (with setf) sets the after-function 
              for the given display. If after-function is non-nil, it is a function that is called after every protocol 
              request is generated, even those inside an explicit with-display
              , but never called from inside the after-function
              . The function is called inside the effective with-display
               for the associated request. The default value is nil
              . This can be set, for example, to #'display-force-output or #' 
              display-finish-output.
             
              
                after-function -- Type function or null.
             | 
     
     
    
      
      
      
        
          | display-force-output | display | Function | 
      
        
          |  | 
              
                display
              
                A display 
                object.
             
              Forces any buffered output to be sent to the X server.
       | 
     
     
    
      
      
      
        
          | display-finish-output | display | Function | 
      
        
          |  | 
              
                display
              
                A display 
                object.
             
              Forces any buffered output to be sent to the X server and then 
              waits until all requests have been received and processed. Any 
              errors generated are read and handled by the display error 
              handler. Any events generated by output requests are read and 
              stored in the event queue.
       | 
     
     
    
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