function DoOnFolderChanging: Boolean; dynamic;
DYNAMIC bool __fastcall DoOnFolderChanging();
Call OnFolderChanging event method if defined.
DoOnFolderChanging calls the OnFolderChanging event, if the event is defined. DoOnFolderChanging is called when a directory is opened or closed from the dialog. This can happen when the user double-clicks on a directory, clicks the Up arrow, or uses the list box at the top of the dialog to navigate through the directory structure. The event occurs after the change.