Displays a standard file dialog for the user to choose a folder.
Built-in Message handler
answer folder prompt [with defaultPath] [as sheet]
answer folder "Please choose a folder:"
if it is empty then answer folder chooseMsg as sheet
answer folder "Where is the data?" with "../data_stacks/recent"
Use the answer folder command when you want the user to choose a folder, for example, as a destination for exported files.
Parameters: The prompt is a string (or any expression that evaluates to a string). If you specify empty, no prompt appears.
The defaultPath is the name and location of the folder whose contents are listed when the dialog box appears. If no defaultPath is specified, the dialog box lists the contents of the last folder you used with a file dialog box.
If the as sheet form is used, the dialog box appears as a sheet on OS X systems. On other systems, the as sheet form has no effect and the dialog box appears normally. Attempting to open a sheet from within another sheet displays the second stack as a modal dialog box instead. To give a dialog box a prompt when using the as sheet form a non-empty title must be provided. This will cause the prompt to appear in the same place it would if as sheet was not being used.
If the systemFileSelector property is set to false, LiveCode's built-in dialog box is used instead of the operating system's standard file dialog.