This function prompts the user to select an existing folder. It does this by displaying the standard "Get File" dialog shown below (its appearance may be different on some systems). If the user selects a folder, then the folder's name is returned in folderName$, and a reference number for the folder is returned in refNumVar% (which must be a short integer variable). If the selected folder is in a volume's root directory, the refNumVar% will return a volume reference number; otherwise, it will return a working directory reference number. If the user cancels the dialog, then the function returns an empty (zero-length) string, and it sets refNumVar% to zero.
The information contained in folderName$ is the correct name for the folder but is not of any real value except to determine that the user has selected Choose instead of Cancel. Only the volume reference number is necessary when using FB's file handling routines.
If the global variable gFBUseNavServices is non-zero, FB switches to the more modern Navigation Services dialog. If the FSSpec version of the call is used, gFBUseNavServices is assumed to be _zTrue.
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If you are programming for Carbon, the gFBUseNavServices = _zTrue statement is required.