Add dynamic instructions

IPython/html/static/tree/js/notebooklist.js

@@ -493,6 +493,13 b' define(['
         }
         // Update total counter
         $('#counter-select-all').html(checked===0 ? ' ' : checked);
+
+        // If at aleast on item is selected, hide the selection instructions.
+        if (checked > 0) {
+            $('.dynamic-instructions').hide();
+        } else {
+            $('.dynamic-instructions').show();
+        }
     };
 
     NotebookList.prototype.add_link = function (model, item) {

IPython/html/static/tree/less/tree.less

@@ -322,3 +322,8 b' ul#new-menu {'
 .shutdown-button {
     display: none;
 }
+
+.dynamic-instructions {
+    display: inline-block;
+    padding-top: @dashboard_tb_pad;
+}

IPython/html/templates/tree.html

@@ -25,6 +25,9 b' data-terminals-available="{{terminals_available}}"'
         <div id="notebooks" class="tab-pane active">
           <div id="notebook_toolbar" class="row">
             <div class="col-sm-8 no-padding">
+              <div class="dynamic-instructions">
+                Select items to perform actions on them.
+              </div>
               <div class="dynamic-buttons">
                   <button title="Duplicate selected" class="duplicate-button btn btn-default btn-xs">Duplicate</button>
                   <button title="Rename selected" class="rename-button btn btn-default btn-xs">Rename</button>