src/java.desktop/share/classes/javax/swing/plaf/basic/BasicComboBoxUI.java

@@ -148,10 +148,12 @@
     /**
      * The {@code KeyListener} listens to events.
      */
     protected KeyListener popupKeyListener;
 
+    private MouseWheelListener mouseWheelListener;
+
     // This is used for knowing when to cache the minimum preferred size.
     // If the data in the list changes, the cached value get marked for recalc.
     // Added to the current JComboBox model
     /**
      * This protected field is implementation specific. Do not access directly

@@ -411,10 +413,14 @@
         if ( comboBox.getModel() != null ) {
             if ( (listDataListener = createListDataListener()) != null ) {
                 comboBox.getModel().addListDataListener( listDataListener );
             }
         }
+
+        if ((mouseWheelListener = createMouseWheelListener()) != null) {
+            comboBox.addMouseWheelListener(mouseWheelListener);
+        }
     }
 
     /**
      * Uninstalls the default colors, default font, default renderer,
      * and default editor from the combo box.

@@ -457,10 +463,13 @@
         if ( comboBox.getModel() != null ) {
             if ( listDataListener != null ) {
                 comboBox.getModel().removeListDataListener( listDataListener );
             }
         }
+        if (mouseWheelListener != null) {
+            comboBox.removeMouseWheelListener(mouseWheelListener);
+        }
     }
 
     /**
      * Creates the popup portion of the combo box.
      *

@@ -570,10 +579,14 @@
             handler = new Handler();
         }
         return handler;
     }
 
+    private MouseWheelListener createMouseWheelListener() {
+        return getHandler();
+    }
+
     //
     // end UI Initialization
     //======================
 
 

@@ -1721,11 +1734,12 @@
     //
     // Shared Handler, implements all listeners
     //
     private class Handler implements ActionListener, FocusListener,
                                      KeyListener, LayoutManager,
-                                     ListDataListener, PropertyChangeListener {
+                                     ListDataListener, PropertyChangeListener,
+                                     MouseWheelListener {
         //
         // PropertyChangeListener
         //
         public void propertyChange(PropertyChangeEvent e) {
             String propertyName = e.getPropertyName();

@@ -1995,11 +2009,11 @@
         // from the editor may be handled by the JComboBox in which case, the
         // enterPressed action will always be invoked.
         public void actionPerformed(ActionEvent evt) {
             Object item = comboBox.getEditor().getItem();
             if (item != null) {
-             if(!comboBox.isPopupVisible() && !item.equals(comboBox.getSelectedItem())) {
+                if (!comboBox.isPopupVisible() && !item.equals(comboBox.getSelectedItem())) {
               comboBox.setSelectedItem(comboBox.getEditor().getItem());
              }
              ActionMap am = comboBox.getActionMap();
              if (am != null) {
                 Action action = am.get("enterPressed");

@@ -2009,10 +2023,14 @@
                                            evt.getModifiers()));
                 }
             }
        }
    }
+
+        public void mouseWheelMoved(MouseWheelEvent e) {
+            e.consume();
+        }
   }
 
     class DefaultKeySelectionManager implements JComboBox.KeySelectionManager, UIResource {
         private String prefix = "";
         private String typedString = "";