- 
        callback 
      
- 
        A function that represents a connection between a contact and the rest
        of an application program. A contact calls a callback function in
        order to report the results of the user interface component that it
        represents. 
      
- 
        children 
      
- 
        First-level subwindows of a window. 
      
- 
        class event 
      
- 
        Event translations that belong to all instances of a contact class. A
        class event translations translation is created by the
        defevent macro. 
      
- 
        class resources 
      
- 
        Resources defined for each instance of a contact class. Also see
        constraint resources. 
      
- 
        click 
      
- 
        A
        :button-press
        event followed immediately by a
        :button-release
        event for the same button, with no intervening change in pointer
        position or modifier key state. 
      
- 
        client 
      
- 
        An application program connects to the window system server by some
        interprocess communication (IPC) path, such as a TCP connection or a
        shared memory buffer. This program is referred to as a client
        of the window system server. More precisely, the client is the IPC
        path itself. A program with multiple paths open to the server is
        viewed as multiple clients by the protocol. Resource lifetimes are
        controlled by connection lifetimes, not by program lifetimes. 
      
- 
        clipping regions 
      
- 
        In a graphics context, a bitmap or list of rectangles can be specified
        to restrict output to a particular region of the window. The image
        defined by the bitmap or rectangles is called a clipping
        region. 
      
- 
        colormap 
      
- 
        A set of entries defining color values. The colormap associated with a
        window is used to display the contents of the window. Each pixel value
        indexes the colormap to produce RGB values that drive the guns of a
        monitor. Depending on hardware limitations, one or more colormaps can
        be installed at one time, such that windows associated with those maps
        display with correct colors. 
      
- 
        composite 
      
- 
        A subclass of contact representing contacts that are the
        parents of other contacts. A composite provides geometry management
        and input focus management services for the contacts that are its
        children. 
      
- 
        complete resource class 
      
- 
        A list of symbols containing the class of the contact, the class of
        the contact's parent (and so on), and the class of the
        contact-display to which the contact belongs. The complete
        resource class is one of the two items used as a key by a CLUE
        application in order to access a contact resource value in a resource
        database. 
      
- 
        complete resource name 
      
- 
        A list of symbols containing the name of the contact, the
        name of the contact's parent (and so on), and the name
        of the contact-display to which the contact belongs. The
        complete resource name is one of the two items used as a key by a CLUE
        application in order to access a contact resource value in a resource
        database. 
      
- 
        connection 
      
- 
        The IPC path between the server and client program. A client program
        typically has one connection to the server over which requests and
        events are sent. 
      
- 
        constraint resources 
      
- 
        Resources defined for each child belonging to a member of a composite
        class. Constraint resources are typically used to control the parent's
        geometry management policy. Also see class resources. 
      
- 
        contact 
      
- 
        The basic CLUE object for programming a user interface. 
      
- 
        contact-display 
      
- 
        The CLUE object type that represents a connection to an X server and
        that supports an event loop for application input. 
      
- 
        contact initialization 
      
- 
        The process of collecting initial values for all contact attributes.
        No server resources (windows and so on) are actually allocated until
        contact realization. 
      
- 
        contact realization 
      
- 
        The process of allocating contact resources. This process completes
        contact creation. 
      
- 
        containment 
      
- 
        A window contains the pointer if the window is viewable and the hot
        spot of the cursor is within a visible region of the window or a
        visible region of one of its inferiors. The border of the window is
        included as part of the window for containment. The pointer is in a
        window if the window contains the pointer but no inferior contains the
        pointer. 
      
- 
        content 
      
- 
        The single child of a shell. The basic geometry management policy
        implemented by the shell class constrains a shell and its
        content to have the same width and height; size changes to one are
        automatically applied to the other. 
      
- 
        coordinate system 
      
- 
        The coordinate system has x horizontal and y vertical, with the origin
        [0, 0] at the upper left. Coordinates are discrete and are in terms of
        pixels. Each window and pixmap has its own coordinate system. For a
        window, the origin is at the inside upper left, inside the border. 
      
- 
        cursor 
      
- 
        The visible shape of the pointer on a screen. It consists of a
        hot-spot, a source bitmap, a shape bitmap, and a pair of colors. The
        cursor defined for a window controls the visible appearance when the
        pointer is in that window.