diff -r 5dc02b23752f -r 3e2da88830cd src/gui/widgets/qcombobox.cpp
--- a/src/gui/widgets/qcombobox.cpp	Tue Jul 06 15:10:48 2010 +0300
+++ b/src/gui/widgets/qcombobox.cpp	Wed Aug 18 10:37:55 2010 +0300
@@ -704,6 +704,11 @@
 {
     emit resetButton();
     combo->update();
+    // QGraphicsScenePrivate::removePopup closes the combo box popup, it hides it non-explicitly.
+    // Hiding/showing the QComboBox after this will unexpectedly show the popup as well.
+    // Re-hiding the popup container makes sure it is explicitly hidden.
+    if (QGraphicsProxyWidget *proxy = graphicsProxyWidget())
+        proxy->hide();
 }
 
 void QComboBoxPrivateContainer::mousePressEvent(QMouseEvent *e)