=== modified file 'libunity-2d-private/src/unity2dpanel.cpp'
--- libunity-2d-private/src/unity2dpanel.cpp	2011-09-27 13:58:46 +0000
+++ libunity-2d-private/src/unity2dpanel.cpp	2011-12-10 22:48:37 +0000
@@ -27,6 +27,7 @@
 // Qt
 #include <QApplication>
 #include <QDesktopWidget>
+#include <QMoveEvent>
 #include <QPainter>
 #include <QPropertyAnimation>
 #include <QHBoxLayout>
@@ -44,6 +45,7 @@
     Unity2dPanel::Edge m_edge;
     mutable IndicatorsManager* m_indicatorsManager;
     QHBoxLayout* m_layout;
+    int m_screen;
     QPropertyAnimation* m_slideInAnimation;
     QPropertyAnimation* m_slideOutAnimation;
     bool m_useStrut;
@@ -97,7 +99,11 @@
     void updateGeometry()
     {
         QDesktopWidget* desktop = QApplication::desktop();
-        const QRect screen = desktop->screenGeometry(q);
+        // use the screen number set by moveEvent(): at the time
+        // showEvent() is called, the screen number associated with
+        // this widget might not have been updated to reflect the
+        // final position.
+        const QRect screen = desktop->screenGeometry(m_screen);
         const QRect available = desktop->availableGeometry(q);
 
         QRect rect;
@@ -105,7 +111,7 @@
         case Unity2dPanel::LeftEdge:
             if (QApplication::isLeftToRight()) {
                 rect = QRect(screen.left(), available.top(), q->width(), available.height());
-                rect.moveLeft(m_delta);
+                rect.moveLeft(screen.left() + m_delta);
             } else {
                 rect = QRect(screen.right() - q->width(), available.top(), q->width(), available.height());
                 rect.moveRight(screen.right() - m_delta);
@@ -113,7 +119,7 @@
             break;
         case Unity2dPanel::TopEdge:
             rect = QRect(screen.left(), screen.top(), screen.width(), q->height());
-            rect.moveTop(m_delta);
+            rect.moveTop(screen.top() + m_delta);
             break;
         }
 
@@ -148,6 +154,8 @@
 : QWidget(parent)
 , d(new Unity2dPanelPrivate)
 {
+    QDesktopWidget* desktop = QApplication::desktop();
+
     d->q = this;
     d->m_edge = Unity2dPanel::TopEdge;
     d->m_indicatorsManager = 0;
@@ -157,6 +165,7 @@
     d->m_layout = new QHBoxLayout(this);
     d->m_layout->setMargin(0);
     d->m_layout->setSpacing(0);
+    d->m_screen = desktop->primaryScreen();
 
     d->m_slideInAnimation = new QPropertyAnimation(this);
     d->m_slideInAnimation->setTargetObject(this);
@@ -179,7 +188,7 @@
         setAutoFillBackground(true);
     }
     
-    connect(QApplication::desktop(), SIGNAL(workAreaResized(int)), SLOT(slotWorkAreaResized(int)));
+    connect(desktop, SIGNAL(workAreaResized(int)), SLOT(slotWorkAreaResized(int)));
 }
 
 Unity2dPanel::~Unity2dPanel()
@@ -219,6 +228,13 @@
     d->m_slideOutAnimation->setEndValue(-panelSize());
 }
 
+void Unity2dPanel::moveEvent(QMoveEvent* event)
+{
+  QWidget::moveEvent(event);
+  QDesktopWidget* desktop = QApplication::desktop();
+  d->m_screen = desktop->screenNumber(event->pos());
+}
+
 void Unity2dPanel::resizeEvent(QResizeEvent* event)
 {
     QWidget::resizeEvent(event);

=== modified file 'libunity-2d-private/src/unity2dpanel.h'
--- libunity-2d-private/src/unity2dpanel.h	2011-09-28 13:08:41 +0000
+++ libunity-2d-private/src/unity2dpanel.h	2011-12-10 22:29:15 +0000
@@ -93,6 +93,7 @@
     virtual void showEvent(QShowEvent*);
     virtual void resizeEvent(QResizeEvent*);
     virtual void paintEvent(QPaintEvent*);
+    virtual void moveEvent(QMoveEvent *);
 
 private Q_SLOTS:
     void slotWorkAreaResized(int screen);

=== modified file 'panel/app/panelmanager.cpp'
--- panel/app/panelmanager.cpp	2011-09-27 13:58:46 +0000
+++ panel/app/panelmanager.cpp	2011-12-10 22:43:25 +0000
@@ -122,8 +122,10 @@
     for(int i = 0; i < desktop->screenCount(); ++i) {
         Unity2dPanel* panel = instantiatePanel(i);
         m_panels.append(panel);
-        panel->show();
+        // perform move() first, so that the destination screen is known by the time 
+        // show() is called and the edge length is computed.
         panel->move(desktop->screenGeometry(i).topLeft());
+        panel->show();
     }
     connect(desktop, SIGNAL(screenCountChanged(int)), SLOT(onScreenCountChanged(int)));
 
@@ -198,8 +200,8 @@
             panel = instantiatePanel(leftmost);
             m_panels.append(panel);
         }
-        panel->show();
         panel->move(desktop->screenGeometry(leftmost).topLeft());
+        panel->show();
 
         /* Update the position of other existing panels, and instantiate new
            panels as needed. */
@@ -214,8 +216,8 @@
                 panel = instantiatePanel(screen);
                 m_panels.append(panel);
             }
+            panel->move(desktop->screenGeometry(screen).topLeft());
             panel->show();
-            panel->move(desktop->screenGeometry(screen).topLeft());
             ++i;
         }
     }