HTML tree: Add tree.focus()

And fix shortcut key for selecting library

chrome/content/zotero/libraryTree.js

@@ -72,6 +72,17 @@ var LibraryTree = class LibraryTree extends React.Component {
 		Zotero.crash();
 	}
 	
+	focus() {
+		this.tree.focus();
+		// If no rows selected, select first visible row
+		if (!this.tree.selection.count) {
+			this.tree.selection.select(
+				// TODO: Return -1 when no rows, and skip selection here
+				this.tree._jsWindow.getFirstVisibleRow()
+			);
+		}
+	}
+
 	getParentIndex = (index) => {
 		var thisLevel = this.getLevel(index);
 		if (thisLevel == 0) return -1;

chrome/content/zotero/zoteroPane.js

@@ -759,7 +759,7 @@ var ZoteroPane = new function()
 		try {
 			switch (command) {
 				case 'library':
-					document.getElementById('zotero-collections-tree').focus();
+					this.itemsView.focus();
 					break;
 				case 'quicksearch':
 					document.getElementById('zotero-tb-search').select();