Mouse scrolling of buttonbar works the same as the treeview.

issue 4062

Change-Id: I70082e47c387462e656a566e72ee390cba331770
Reviewed-on: http://gerrit.dmdirc.com/1199
Automatic-Compile: Gregory Holmes <greg@dmdirc.com>
Reviewed-by: Gregory Holmes <greg@dmdirc.com>

src/com/dmdirc/addons/ui_swing/framemanager/buttonbar/ButtonBar.java

             buttonPanel = new ButtonPanel(new MigLayout("ins rel, fill, flowy"),
                     this);
         }
+        scrollPane.getViewport().addMouseWheelListener(buttonPanel);
         scrollPane.getViewport().add(buttonPanel);
     }
 
         return buttonHeight;
     }
 
+    /**
+     * Returns the button object of the current selected window
+     *
+     * @return Button object for the current selected window
+     */
+    public FrameToggleButton getSelectedButton() {
+        return getButton(selected);
+    }
+
     /** {@inheritDoc} */
     @Override
     public void setParent(final JComponent parent) {
             @Override
             public void run() {
                 ButtonBar.this.parent = parent;
-                scrollPane.setSize(parent.getWidth(), parent.getHeight());
-
-                parent.setLayout(new MigLayout("ins 0"));
-                parent.add(scrollPane);
+                parent.setLayout(new MigLayout("ins 0, fill"));
+                parent.add(scrollPane, "top, left");
                 parent.addComponentListener(ButtonBar.this);
             }
         });
                             buttonWidth, buttonHeight));
                 buttonPanel.add(button);
                 if (!window.getChildren().isEmpty()) {
-                    final ArrayList childList = new ArrayList<FrameContainer<?>>(
-                            window.getChildren());
+                    final ArrayList<FrameContainer<?>> childList = new ArrayList
+                            <FrameContainer<?>>(window.getChildren());
                     if (sortChildWindows) {
                          Collections.sort(childList, new FrameContainerComparator());
                     }
         buttonPanel.setVisible(false);
         buttonPanel.removeAll();
 
-        final ArrayList windowList = new ArrayList<FrameContainer<?>>(
-                WindowManager.getRootWindows());
+        final ArrayList<FrameContainer<?>> windowList = new
+                ArrayList<FrameContainer<?>>(WindowManager.getRootWindows());
         if (sortRootWindows) {
             Collections.sort(windowList, new FrameContainerComparator());
         }
                 selected = window;
                 button = getButton(window);
                 if (button != null) {
+                    scrollPane.getViewport().scrollRectToVisible(button.getBounds());
                     button.setSelected(true);
                 }
             }
         //Do nothing
     }
 
+    /** {@inheritDoc} */
     @Override
     public void configChanged(String domain, String key) {
         if ("sortrootwindows".equals(key)) {

src/com/dmdirc/addons/ui_swing/framemanager/buttonbar/ButtonPanel.java

  */
 package com.dmdirc.addons.ui_swing.framemanager.buttonbar;
 
+import java.awt.Component;
 import java.awt.Dimension;
 import java.awt.Rectangle;
 
+import java.awt.event.MouseWheelEvent;
+import java.awt.event.MouseWheelListener;
+
 import javax.swing.JPanel;
 import javax.swing.Scrollable;
 
  * @author Simon Mott
  * @since 0.6.4
  */
-public class ButtonPanel extends JPanel implements Scrollable {
+public class ButtonPanel extends JPanel implements Scrollable, MouseWheelListener {
 
     /**
      * A version number for this class. It should be changed whenever the class
         return false;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public void mouseWheelMoved(MouseWheelEvent e) {
+        e.consume();
+        final int selectedIndex = getSelectedIndex();
+        int newIndex = 0;
+        if (e.getWheelRotation() < 0) {
+            //Up
+            newIndex = selectedIndex > 0 ? selectedIndex - 1 :
+                getComponentCount() - 1;
+        } else if (e.getWheelRotation() > 0) {
+            //Down
+            newIndex = (selectedIndex + 1) % getComponentCount();
+        }
+        ((FrameToggleButton) getComponent(newIndex)).getWindow().activateFrame();
+    }
+
+    /**
+     * Gets the component index of the button associated with the current
+     * selected window.
+     *
+     * @return Integer Index for the button of the selected window
+     *
+     * @since 0.6.4
+     */
+    private int getSelectedIndex() {
+        int selectedIndex = 0;
+        final FrameToggleButton selectedButton = buttonBar.getSelectedButton();
+        for (Component c : getComponents()) {
+            if (c == selectedButton) {
+                break;
+            }
+            selectedIndex++;
+        }
+        return selectedIndex;
+    }
+
 }