Update collection context menu once items have loaded

Otherwise, when right-clicking on a collection that's not currently
selected, some of the menu items appear gray at first, and a second
right-click is necessary after the items have loaded. This way the menu
items turn black once the items have loaded.

chrome/content/zotero/xpcom/libraryTreeView.js

@@ -37,6 +37,10 @@ Zotero.LibraryTreeView = function () {
 };
 
 Zotero.LibraryTreeView.prototype = {
+	get initialized() {
+		return this._initialized;
+	},
+	
 	addEventListener: function(event, listener) {
 		if (event == 'load') {
 			// If already initialized run now

chrome/content/zotero/zoteroPane.js

@@ -2338,14 +2338,19 @@ var ZoteroPane = new function()
 				m.loadReport
 			];
 			var s = [m.exportCollection, m.createBibCollection, m.loadReport];
+			
 			if (!this.itemsView.rowCount) {
-				if (!this.collectionsView.isContainerEmpty(this.collectionsView.selection.currentIndex)) {
+				// If no items, it might be because this was a right-click on a different collection
-					disable = [m.createBibCollection, m.loadReport];
+				// and the new collection's items are still loading, so update the menu after loading.
+				// This causes export/createBib/loadReport to appear gray in the menu at first and then
+				// turn black once there are items.
+				if (!this.itemsView.initialized) {
+					this.itemsView.addEventListener('load', function () {
+						this.buildCollectionContextMenu();
+					}.bind(this));
 				}
-				else {
 				disable = s;
 			}
-			}
 			
 			// Adjust labels
 			menu.childNodes[m.editSelectedCollection].setAttribute('label', Zotero.getString('pane.collections.menu.rename.collection'));