have arrow removal hover effect working

assets/javascripts/reporting/group_bys.js

@@ -102,12 +102,24 @@ Reporting.GroupBys = {
     });
   },
 
+  arrow_removal_hover: function(arrow, status) {
+    if (status) {
+      $(arrow).addClassName('arrow_removal_hover');
+    }
+    else {
+      $(arrow).removeClassName('arrow_removal_hover');
+    }
+  },
+
   init_arrow: function(group_by) {
     var arrow = new Element('img', {
       'class': 'arrow in_row arrow_left',
       'id': group_by.identify() + '_arrow'
     });
     //init_arrow_hover_effects(arrow);
+    arrow.observe('mouseover', function() { Reporting.GroupBys.arrow_removal_hover(arrow, true)  });
+    arrow.observe('mouseout',  function() { Reporting.GroupBys.arrow_removal_hover(arrow, false) });
+    arrow.observe('mousedown', function() { Reporting.GroupBys.remove_group_by(arrow) });
     return arrow;
   },
 

assets/stylesheets/reporting.css

@@ -304,7 +304,7 @@ fieldset#filter-settings table td > label {
   background-image: url(../images/group_by_arrow_both_hover_left.png);
 }
 
-.arrow_both_remove {
+.arrow_both.arrow_removal_hover {
   background-image: url(../images/group_by_arrow_both_remove.png);
 }
 
@@ -316,7 +316,7 @@ fieldset#filter-settings table td > label {
   background-image: url(../images/group_by_arrow_left.png);
 }
 
-.arrow_left_remove {
+.arrow_left.arrow_removal_hover {
   background-image: url(../images/group_by_arrow_left_remove.png);
 }