I was looking for a way to disable the File Selection in FDOM. I can see that there is

protected $allowUploadFolderSelection = true;

and

public function allowUploadFolderSelection()
{
$this->allowUploadFolderSelection = true;
}

However there is not way aside from setting $allowUploadFolderSelection = false; to disable the Folder Selection interface. It would seem that at least on a per instance basis there is no way to disable the Folder Selection on FDOM or IDOM. Of course there may be something I am missing here but shouldn't the function be

public function disableUploadFolderSelection() {
$this->allowUploadFolderSelection = falsel;
}

stumbled upon the same issue. will eventually file a pull request on github

This seems to work for me:

	function getCMSFields() {
		$fields = parent::getCMSFields();
		
		// Slideshow 
		$manager = new ImageDataObjectManager(
			$this, 				// Controller
			'Slideshow', 		// Source name
			'SlideshowImage', 	// Source class
			'Attachment', 		// File name on DataObject
			array( 				// Headings 
								
			),
			'getCMSFields_forPopup' // Detail fields (function name or FieldSet object)
			// Filter clause
			// Sort clause
			// Join clause
		);

		$manager->allowUploadFolderSelection = false; 
		$manager->setUploadFolder("Slideshow-Images");
		$fields->addFieldToTab("Root.Content.Slideshow", $manager);

		return $fields;
	}