Control the volume by spinning the mouse wheel over the system tray icon.
--- a/src/systray.cpp
+++ b/src/systray.cpp
@@ -25,6 +25,7 @@
 #include "container.h"
 #include "LastFmSettings.h"
 #include "MooseCommon.h"
+#include <QWheelEvent>
 
 
 TrayIcon::TrayIcon( QObject* parent )
@@ -157,3 +158,20 @@
 {
     m_animationTimer.stop();
 }
+
+
+bool
+TrayIcon::event( QEvent* e )
+{
+    // Beginning with Qt 4.3, QSystemTrayIcon supports wheel events, but only
+    // on X11.  Let's make it adjust the volume.
+    if ( e->type() == QEvent::Wheel )
+    {
+        int numDegrees = ((QWheelEvent*)e)->delta() / 8;
+        int numSteps = numDegrees / 15;
+        int volume = Container::instance().ui.playcontrols.volume->value() + ( 5 * numSteps );
+        Container::instance().ui.playcontrols.volume->setValue( volume );
+        return true;
+    }
+    return QSystemTrayIcon::event( e );
+}
--- a/src/systray.h
+++ b/src/systray.h
@@ -35,6 +35,7 @@
     TrayIcon( QObject* parent );
     void startIpodScrobblingAnimation();
     void stopIpodScrobblingAnimation();
+    virtual bool event( QEvent* e );
 
 public slots:
     void setTrack( const class MetaData &track );
--- a/src/container.h
+++ b/src/container.h
@@ -39,6 +39,7 @@
     Q_OBJECT
 
         static Container* s_instance;
+        friend class TrayIcon;
 
     public:
         Container();