DISPLAYING A DIRECTORY

     The main directory displaying routine is a function. The format rules
     are as follows:

     Display_Directory - this function returns a string of up to 80
     characters in length. The function is passed the full file mask
     including the path and a variable of type integer that will be updated
     with the completion code. For example,

     CHOSEN_FILE := DISPLAY_DIRECTORY('C:\*.PAS',ERRCODE)


     When the function is called, a directory display of all the files
     matching the file mask will be displayed in a window. The user will be
     able to select a file and the chosen file is returned.

     The return codes are:

     0    file chosen (no problems)
     1    user escaped (only if AllowEsc is true)
     2    not enough memory (listing not displayed)
     99   internal (unexpected) error