Added dropdown submenu CSS

IPython/html/static/notebook/less/menubar.less

@@ -1,37 +1,45
 #menubar {
 }
 
 #menubar .navbar-inner {
   min-height: 28px;
   border-top: 1px;
   border-radius: 0px 0px @border-radius-base @border-radius-base;
 }
 
 #menubar .navbar {
   margin-bottom: 8px;
 }
 
 .nav-wrapper {
   border-bottom: 1px solid @navbar-default-border;
 }
 
 #menubar li.dropdown {
   line-height: 12px;
 }
 
 i.menu-icon {
   // add padding to account for float-right
   padding-top: 4px;
 }
 
 ul#help_menu li a{
     overflow: hidden;
     padding-right: 2.2em;
     i {
         margin-right: -1.2em;
     }
 }
 
 ul#menus {
   float: left;
 }
+
+// http://www.bootply.com/86684
+.dropdown-submenu{position:relative;}
+.dropdown-submenu>.dropdown-menu{top:0;left:100%;margin-top:-6px;margin-left:-1px;-webkit-border-radius:0 6px 6px 6px;-moz-border-radius:0 6px 6px 6px;border-radius:0 6px 6px 6px;}
+.dropdown-submenu:hover>.dropdown-menu{display:block;}
+.dropdown-submenu>a:after{display:block;content:" ";float:right;width:0;height:0;border-color:transparent;border-style:solid;border-width:5px 0 5px 5px;border-left-color:#cccccc;margin-top:5px;margin-right:-10px;}
+.dropdown-submenu:hover>a:after{border-left-color:#ffffff;}
+.dropdown-submenu.pull-left{float:none;}.dropdown-submenu.pull-left>.dropdown-menu{left:-100%;margin-left:10px;-webkit-border-radius:6px 0 6px 6px;-moz-border-radius:6px 0 6px 6px;border-radius:6px 0 6px 6px;}

IPython/html/static/notebook/less/toolbar.less

@@ -1,33 +1,38
 .toolbar {
     padding: 0px 10px;
     margin-top: -5px;
 
     select, label {
         width: auto;
         vertical-align:middle;
         margin-right:2px;
         margin-bottom:0px;
         display: inline;
         font-size: 92%;
         margin-left:0.3em;
         margin-right:0.3em;
         padding: 0px;
         padding-top: 3px;
     }
     .btn {
         padding: 2px 8px;
     }
 }
 
 .toolbar .btn-group {
   margin-top: 0px;
+  margin-left: 5px;
 }
 
 .toolbar-inner {
   border: none !important;
   .box-shadow(none) !important;
 }
 
 #maintoolbar {
   margin-bottom: 0px;
 }
+
+#maintoolbar .navbar-text {
+  float: none;
+}