add text placeholder for kernels with no logo

capital first initial on gray field

IPython/html/static/notebook/js/kernelselector.js

@@ -126,7 +126,8 b' define(['
         this.events.on('spec_changed.Kernel', function(event, data) {
             that.current_selection = data.name;
             $("#kernel_indicator").find('.kernel_indicator_name').text(data.display_name);
-            that.element.find("#current_kernel_logo").attr("src", that.notebook.base_url+"kernelspecs/"+data.name+"/logo-64x64.png");
+            that.element.find("img.current_kernel_logo").attr("src", that.notebook.base_url + "kernelspecs/" + data.name + "/logo-64x64.png");
+            that.element.find("div.current_kernel_logo").text(data.display_name.slice(0,1).toUpperCase());
         });
 
         this.events.on('kernel_created.Session', function(event, data) {
@@ -139,12 +140,15 b' define(['
             }
         });
         
-        var logo_img = this.element.find("#current_kernel_logo");
+        var logo_img = this.element.find("img.current_kernel_logo");
+        var logo_div = this.element.find("div.current_kernel_logo");
         logo_img.on("load", function() {
+            logo_div.hide();
             logo_img.show();
         });
         logo_img.on("error", function() {
             logo_img.hide();
+            logo_div.show();
         });
     };
 

IPython/html/static/notebook/less/kernelselector.less

@@ -2,9 +2,17 b''
     margin-right: 1em;
     .pull-right();
     
-    & > img#current_kernel_logo {
+    .current_kernel_logo {
+        display: none;
         .navbar-vertical-align(32px);
         width: 32px;
         height: 32px;
     }
+    
+    div.current_kernel_logo {
+        background-color: darken(@navbar-default-bg, 10%);
+        font-size: 24px;
+        text-align: center;
+        text-decoration: bold;
+    }
 }

IPython/html/static/style/style.min.css

@@ -9677,12 +9677,19 b' select[multiple].celltoolbar select {'
   float: right !important;
   float: right;
 }
-#kernel_logo_widget > img#current_kernel_logo {
+#kernel_logo_widget .current_kernel_logo {
+  display: none;
   margin-top: -1px;
   margin-bottom: -1px;
   width: 32px;
   height: 32px;
 }
+#kernel_logo_widget div.current_kernel_logo {
+  background-color: #dfdfdf;
+  font-size: 24px;
+  text-align: center;
+  text-decoration: bold;
+}
 #menubar {
   box-sizing: border-box;
   -moz-box-sizing: border-box;

IPython/html/templates/notebook.html

@@ -43,7 +43,8 b' class="notebook_app"'
 </span>
 
 <span id="kernel_logo_widget">
-  <img id="current_kernel_logo"/>
+  <img class="current_kernel_logo"/>
+  <div class="current_kernel_logo"></div>
 </span>
 
 {% endblock headercontainer %}