c

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.