TBrowse
 Provide objects for browsing table-oriented data
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 Description

     A TBrowse object is a general purpose browsing mechanism for
     table-oriented data.  TBrowse objects provide a sophisticated
     architecture for acquiring, formatting, and displaying data.  Data
     retrieval and file positioning are performed via user-supplied code
     blocks, allowing a high degree of flexibility and interaction between
     the browsing mechanism and the underlying data source.  The format of
     individual data items can be precisely controlled via the TBColumn data
     retrieval code blocks; overall display formatting and attributes can be
     controlled by sending appropriate messages to the TBrowse object.

     Note:  TBrowse has a memory limit of 200 fields.

     A TBrowse object relies on one or more TBColumn objects.  A TBColumn
     object contains the information necessary to define a single column of
     the browse table (see TBColumn class in this chapter).

     During operation, a TBrowse object retrieves data by evaluating code
     blocks.  The data is organized into rows and columns and displayed
     within a specified rectangular region of the screen.  The TBrowse object
     maintains an internal browse cursor.  The data item on which the browse
     cursor rests is displayed in a highlighted color.  (The actual screen
     cursor is also positioned to the first character of this data item.)

     Initially, the browse cursor is placed on the data item at the top left
     of the browse display.  Messages can then be sent to the TBrowse object
     to navigate the displayed data, causing the browse cursor to move.
     These messages are normally sent in response to user keystrokes.

     New data is automatically retrieved as required by navigation requests.
     When navigation proceeds past the edge of the visible rectangle, rows or
     columns beyond that edge are automatically brought into view.  When new
     rows are brought into view, the underlying data source is repositioned by
     evaluating a code block.

     Note:  TBrowse objects do not clear the entire window before output
     during redisplay operations.  Part of the window may still be cleared
     when data from the existing display is scrolled.

 Examples

     For fully operational examples of a TBrowse object, refer to
     "Introduction to TBrowse" in the Programming and Utilities Guide and to
     TbDemo.prg located in \CLIP53\SOURCE\SAMPLE.