diff --git a/resources/ui/dialog/CategoryEditor.js b/resources/ui/dialog/CategoryEditor.js
index 647229d..f9fce34 100644
--- a/resources/ui/dialog/CategoryEditor.js
+++ b/resources/ui/dialog/CategoryEditor.js
@@ -1,239 +1,243 @@
 ( function( $, bs, mw ){
 	bs.util.registerNamespace( 'ext.InsertCategory.ui.dialog' );
 
 	ext.InsertCategory.ui.dialog.CategoryEditor = function( config ){
 		ext.InsertCategory.ui.dialog.CategoryEditor.parent.call( this, $.extend( {
 			size: 'large'
 		}, config ) );
 
 		this.pageId = mw.config.get( 'wgArticleId' );
 
 		this.$element.addClass( 'bs-insert-category-editor-dialog' );
 	};
 
 	OO.inheritClass( ext.InsertCategory.ui.dialog.CategoryEditor, OO.ui.ProcessDialog );
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.static.name = 'BSInsertCategoryEditorDialog';
 	ext.InsertCategory.ui.dialog.CategoryEditor.static.title = mw.message( 'bs-insertcategory-edit-dialog-title' ).text();
 	ext.InsertCategory.ui.dialog.CategoryEditor.static.actions = [
 		{
 			action: 'submit',
 			label: mw.message( 'bs-insertcategory-edit-dialog-button-submit' ).text(),
 			flags: [ 'primary', 'progressive' ]
 		},
 		{
 			action: 'cancel',
 			label: mw.message( 'bs-insertcategory-edit-dialog-button-cancel' ).text(),
 			flags: [ 'safe' ]
 		}
 	];
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.initialize = function() {
 		ext.InsertCategory.ui.dialog.CategoryEditor.parent.prototype.initialize.call( this );
 
 		this.addSelector();
 		this.getPageCategories().done( function( selected, implicit ) {
 			this.popPending();
 			this.selector.setValue( selected );
 			this.selector.setDisabled( false );
 			this.selector.focus();
 			this.addImplicitCategorySection( implicit );
 			this.addCategoryTree();
 			this.updateSize();
 		}.bind( this ) ).fail( function() {
 			this.popPending();
 
 			var error = new OO.ui.Error(
 				mw.message( 'bs-insertcategory-edit-dialog-page-categories-get-error-message' ).text(),
 				{
 					recoverable: false
 				}
 			);
 			this.showErrors( error );
 		}.bind( this ) );
 
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.getPageCategories = function() {
 		this.pushPending();
 		var dfd = $.Deferred();
 
 		new mw.Api().get( {
 			action: 'bs-categorylinks-store',
 			start: 0,
 			limit: 25,
 			filter: JSON.stringify( [ {
 				type: 'numeric',
 				operator: 'eq',
 				property: 'page_id',
 				value: this.pageId
 			} ] )
 		} ).done( function( response ) {
 			var selected = [], implicit = [];
 			for ( var i = 0; i < response.results.length; i++ ) {
 				var result = response.results[i];
 				if ( result.category_is_explicit === true ) {
 					selected.push( result.category_title );
 				}
 				else {
 					implicit.push( {
 						title: result.category_title,
 						href: result.category_link
 					} );
 				}
 			}
 
 			dfd.resolve( selected, implicit );
 		} ).fail( function( error ) {
 			console.log( error );
 			dfd.reject();
 		} );
 
 		return dfd.promise();
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.addSelector = function() {
 		this.selector = new OOJSPlus.ui.widget.CategoryMultiSelectWidget( {
 			allowArbitrary: true,
 			$overlay: true,
 			disabled: true
 		} );
 
 		var selectorLayout = new OO.ui.FieldLayout( this.selector, {
 			label: mw.message( 'bs-insertcategory-edit-dialog-input-label' ).text(),
 			align: 'top'
 		} );
 
 		this.$body.append( new OO.ui.PanelLayout( {
 			padded: true,
 			expanded: false,
 			$content: selectorLayout.$element
 		} ).$element );
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.addImplicitCategorySection = function( implicit ) {
 		if ( implicit.length === 0 ) {
 			return;
 		}
 
 		var implicitCatLayout = new OO.ui.FieldsetLayout( {
 			label:  mw.message( 'bs-insertcategory-edit-dialog-implicit-categories-label' ).text(),
 			help: mw.message( 'bs-insertcategory-edit-dialog-implicit-categories-help' ).text()
 		} ),
 		implicitCatTextLayout = new OO.ui.HorizontalLayout();
 
 		var html = '';
 		for ( var i = 0; i < implicit.length; i++ ) {
 			html = html + '<span class="oo-ui-tagItemWidget">' + implicit[i]['title'] + '</span>';
 		}
 
 		var htmlSnippet = new OO.ui.HtmlSnippet( html );
 
 		implicitCatText = new OO.ui.Element( {
 			content: [ htmlSnippet ]
 	 	} );
 
 		implicitCatTextLayout.addItems( [ implicitCatText ] );
 		implicitCatLayout.addItems( [ implicitCatTextLayout ] );
 
 		this.$body.append( new OO.ui.PanelLayout( {
 			padded: true,
 			expanded: false,
 			$content: implicitCatLayout.$element
 		} ).$element );
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.getActionProcess = function( action ) {
 		if ( action === 'submit' ) {
 			return new OO.ui.Process( function () {
 				var categories = this.selector.getValue();
 
 				bs.api.tasks.exec( 'wikipage', 'setCategories', {
 					page_id: this.pageId,
 					categories: categories
 				} )
 				.done( function() {
 					window.location.reload();
 				} )
 				.fail( function( result ) {
 					console.dir( result );
 				} );
 
 				this.close();
 			}.bind( this ) );
 		}
 
 		if ( action === 'cancel' ) {
 			return new OO.ui.Process( function () {
 				this.close();
 			}.bind( this ) );
 		}
 
 		return ext.InsertCategory.ui.dialog.CategoryEditor.parent.prototype.getActionProcess.call( this, action );
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.getBodyHeight = function() {
 		return this.$body.outerHeight( true ) + 30;
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.onTreeItemSelected = function( item ) {
 		var text = item.label,
 			value = this.selector.getValue();
 
  		if ( value.indexOf( text ) !== -1 ) {
  			value.splice( value.indexOf( text ), 1 );
 		} else {
  			value.push( text );
 		}
 		this.selector.setValue( value );
 	};
 
 	ext.InsertCategory.ui.dialog.CategoryEditor.prototype.addCategoryTree = function() {
 		this.categoryTree = new OOJSPlus.ui.data.StoreTree(
 			{
 				store: {
 					action: 'bs-category-treestore',
 					rootNode: 'src'
-				}
+				},
+				expanded: false,
+				id: 'category-editor-tree',
+				labelledby: 'bs-insertcategory-edit-dialog-tree-view-tgl'
 			}
 		);
 		this.categoryTree.connect( this, {
 			loaded: function() {
 				this.updateSize();
 			},
 			'collapse-expand': function() {
 				this.updateSize();
 			},
 			itemSelected: function( item ) {
 				this.onTreeItemSelected( item );
 			}
 		} );
 		this.categoryTree.$element.hide();
 		this.categoryTree.$element.css( {
 			'max-height': '500px',
 			'padding-left': '20px',
 			'overflow-y': 'auto'
 		} );
 
 		var expander = new OO.ui.ButtonWidget( {
 			label: mw.message( 'bs-insertcategory-edit-dialog-tree-view' ).text(),
 			framed: false,
-			flags: [ 'primary', 'progressive' ]
+			flags: [ 'primary', 'progressive' ],
+			id: 'bs-insertcategory-edit-dialog-tree-view-tgl'
 		} );
 		expander.connect( this, {
 			click: function() {
 				this.categoryTree.$element.toggle();
 				this.updateSize();
 			}
 		} );
 
 		this.$body.append( $( '<div>' ).css( {
 			padding: '10px',
 			margin: '0 0 0 10px'
 		} ).append(
 			expander.$element,
 			this.categoryTree.$element
 		) );
 	};
 } )( jQuery, blueSpice, mediaWiki );