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        event 
      
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        Clients receive information asynchronously via events. These
        events can be either asynchronously generated from devices, or
        generated as side effects of client requests. Events are grouped into
        types; events are never sent to a client by the server unless the
        client has specifically asked to be informed of that type of event,
        but clients can force events to be sent to other clients. Events are
        typically reported relative to a window. 
      
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        event compression 
      
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        Ignoring (or compressing) certain redundant input events. Compression
        of redundant events is controlled by the class slots
        compress-exposures and compress-motion, which are shared
        by all instances of a contact class. 
      
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        event loop 
      
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        The fundamental application control structure: wait for an event,
        figure out how to handle it, process the event, then go back and wait
        for the next one. In CLUE, the event loop is implemented using the
        process-next-event function. 
      
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        event mask 
      
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        Events are requested relative to a window. The set of event types a
        client requests relative to a window are described using an event
        mask. 
      
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        event propagation 
      
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        Device-related events propagate from the source window to
        ancestor windows until some client has expressed interest in handling
        that type of event, or until the event is discarded explicitly. 
      
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        event specification 
      
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        A notation for describing a certain sort of event. CLUE input
        processing consists of matching an event with an event specification
        found in a contact's event-translations slot and then calling
        actions associated with the matching event specification. 
      
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        event synchronization 
      
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        Certain race conditions are possible when demultiplexing device events
        to clients (in particular deciding where pointer and keyboard events
        should be sent when in the middle of window management operations).
        The event synchronization mechanism allows synchronous processing of
        device events. 
      
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        event source 
      
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        The smallest window containing the pointer is the source of a
        device related event. 
      
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        event translation 
      
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        The process of determining which contact action functions will be
        executed. An event translation is a list found in a contact's
        event-translations slot associating an event specification with
        one or more action names. Also see class event translations. 
      
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        exposure event 
      
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        Servers do not guarantee to preserve the contents of windows when
        windows are obscured or reconfigured. Exposure events are sent
        to clients to inform them when contents of regions of windows have
        been lost. 
      
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        extension 
      
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        Named extensions to the core protocol can be defined to extend
        the system. Extension to output requests, resources, and event types
        are all possible, and expected.