Pop up a window prompting the user to choose a directory on the target system.
A full directory path if the user selects one or an empty string if they cancel.
-message <message string>
A message to display at the top of the dialog window.
How to normalize the directory the user chooses. The options are: backslash, forwardslash, platform, unix or windows. Backslash will replace all directory separators with backslashes. Forwardslash will replace all directory separators with forward slashes. Platform means to do whatever the current platform does. Unix means to use forward slashes and remove any Windows drive letter (C:, D:, etc...). Windows means to use back slashes and leave any drive letter in place. The default is platform.
-title <title string>
A title string to display in the title bar of the dialog.
-variable <variable name>
A variable name to store the resulting directory in.
-virtualtext <virtual text name>
A virtual text name (without the <% and %>) to store the resulting directory in.