Retain keyboard focus after closing the dropdown

Fixes angular-ui#46.

The fix does two things. First, it actively sets focus
back to the button after closing the dropdown. To do this,
it uses $timeout with a zero timeout value to give angular
time to show the button before changing focus to it.
This is the same as was done previously when showing the dropdown.

There is however a second problem: bootstrap defines a
transition for form_control. This means that it takes some
time before the button is shown. This means that when the
timeout fires and focus() is called, the button is still
hidden and thus cannot be focused.

To work around the second problem, we can either use a
slightly longer timeout (a few 100ms), or we can disable the
transitions. I have chosen to disable the transitions, since
the timeout feels "ugly". This is done in the patch to select.css.

Author: mattiash

src/select.css

@@ -55,3 +55,8 @@
   max-height: 200px;
   overflow-x: hidden;
 }
+
+.ui-select-bootstrap .form-control {
+  -webkit-transition: none;
+  transition: none;
+}

src/select.js

@@ -199,6 +199,12 @@ angular.module('ui.select', [])
     if (ctrl.open) {
       _resetSearchInput();
       ctrl.open = false;
+
+      // Give the button element time to appear again before returning focus to it
+      $timeout(function () {
+        var _selectButton = $element.querySelectorAll("button.ui-select-match");
+        _selectButton[0].focus();
+      });
     }
   };