update dropdown actions

src/Grid/Displayers/DropdownActions.php

@@ -35,17 +35,30 @@ class DropdownActions extends Actions
      */
     protected function addScript()
     {
-        $script = <<<'SCRIPT'
-(function ($) {
-    $('.table-responsive').on('show.bs.dropdown', function () {
-         $('.table-responsive').css("overflow", "inherit" );
+        $script = <<<'JS'
+$(function() {
+  $('.table-responsive').on('shown.bs.dropdown', function(e) {
+    var t = $(this),
+      m = $(e.target).find('.dropdown-menu'),
+      tb = t.offset().top + t.height(),
+      mb = m.offset().top + m.outerHeight(true),
+      d = 20; // Space for shadow + scrollbar.   
+      
+    if (t[0].scrollWidth > t.innerWidth()) {
+      if (mb + d > tb) {
+        t.css('padding-bottom', ((mb + d) - tb));
+      }
+    } else {
+      t.css('overflow', 'visible');
+    }
+  }).on('hidden.bs.dropdown', function() {
+    $(this).css({
+      'padding-bottom': '',
+      'overflow': ''
     });
-    
-    $('.table-responsive').on('hide.bs.dropdown', function () {
-         $('.table-responsive').css("overflow", "auto");
-    })
-})(jQuery);
-SCRIPT;
+  });
+});
+JS;
 
         Admin::script($script);
     }