Move should cancel blur into codecell

IPython/html/static/notebook/js/cell.js

@@ -269,7 +269,7 @@ var IPython = (function (IPython) {
      * @return results {bool} Whether or not to ignore the cell's blur event.
      **/
     Cell.prototype.should_cancel_blur = function () {
-        return IPython.tooltip && IPython.tooltip.is_visible();
+        return false;
     };
 
     /**

IPython/html/static/notebook/js/codecell.js

@@ -411,9 +411,10 @@ var IPython = (function (IPython) {
      **/
     CodeCell.prototype.should_cancel_blur = function () {
         // Cancel this unfocus event if the base wants to cancel or the cell 
-        // completer is open.
+        // completer is open or the tooltip is open.
         return IPython.Cell.prototype.should_cancel_blur.apply(this) ||
-            (this.completer && this.completer.is_visible());
+            (this.completer && this.completer.is_visible()) ||
+            (IPython.tooltip && IPython.tooltip.is_visible());
     };
 
     CodeCell.prototype.select_all = function () {