silverstripe-dms/code/cms/DocumentHtmlEditorFieldToolbar.php

<?php
/**
 * Extends the original toolbar with document picking capability - modified lines are commented.
 */


class DocumentHtmlEditorFieldToolbar extends Extension {

	function updateLinkForm(Form $form) {
		$linkType = null;
		$fieldList = null;
		$fields = $form->Fields();//->fieldByName('Heading');
		foreach($fields as $field) {
			$linkType = ($field->fieldByName('LinkType'));
			$fieldList = $field;
			if ($linkType) break;   //break once we have the object
		}

		$source = $linkType->getSource();
		$source['documentopt'] = 'Download a document';
		$linkType->setSource($source);

		$addExistingField = new DMSDocumentAddExistingField('AddExisting', 'Add Existing');
		$addExistingField->setForm($form);
		$addExistingField->setUseFieldClass(false);
		$fieldList->insertAfter($addExistingField,'Description');

//		Requirements::javascript(SAPPHIRE_DIR . "/thirdparty/behaviour/behaviour.js");
//		Requirements::javascript(SAPPHIRE_DIR . "/javascript/tiny_mce_improvements.js");
//
//		// create additional field, rebase to 'documents' directory
//		$documents = new TreeDropdownField('document', 'Document', 'File', 'ID', 'DocumentDropdownTitle', true);
//		$documents->setSearchFunction(array($this, 'documentSearchCallback'));
//		$baseFolder = Folder::find_or_make(Document::$directory);
//		$documents->setTreeBaseID($baseFolder->ID);


		//return $form;
	}
}