Contacts

In simplest terms, a contact is a kind of window. The behavior of a window object, which is represented in CLX as an instance of the window data type, is completely specified by the X Window System protocol. In CLUE, the class of contact objects is defined to be a subclass of the class of window objects³. Thus, all CLX window functions apply to any contact.

$\framebox[5.5in]{ \hspace*{\fill} {\bf Note} \hspace*{\fill} \parbox[t]{4.5in}{ ... ... argument can be called with a {\tt contact} argument instead.} \hspace*{\fill}}$

As a window, a contact inherits several basic attributes, such as a rectangular geometry (given by the position of its upper left corner, its width, and its height in pixel coordinates), a border width and border color/pattern, a depth (i.e. bits per pixel), and a background color/pattern. Contacts possess a few additional attributes (or slots) not shared by ordinary windows.

name: The name of the contact is a symbol which can be used to access contact resources stored in a resource database. See Section .
parent: All contacts have a parent contact (except for a root contact, which is created automatically by CLUE and which is the ancestor of all contacts on a single display screen). The parent-child relationship is fundamentally one between two windows, as defined by the X Window System. For example, a child window is always visually contained by its parent window, and its position is specified relative to its parent's upper-left corner. However, in CLUE this relationship is extended, with the parent assuming additional responsibilities, such as geometry management (see Section ).
state: A switch which controls the visual effect of the contact on the UI. If the state is :withdrawn, then the contact is invisible and unavailable for input. If the state is :mapped, then the contact is ``viewable'' (i.e. visible unless it is covered by other windows) and available for input. The state can also have a third value — :managed — which is discussed in Section . The default state is :mapped.
event-translations: A list which associates different types of input events with contact actions. This is discussed in more detail in Section .
callbacks: An association list of callback name/function pairs.

Subsections