Sets whether the directory list will monitor the directory for changes.
If monitoring is enabled, the items_changed signal will be emitted when the directory contents change.
When monitoring is turned on after the initial creation of the directory list, the directory is reloaded to avoid missing files that appeared between the initial loading and when monitoring was turned on.
| this |
a `GtkDirectoryList` |
| monitored |
true to monitor the directory for changes |