diff -r 56cd8111b7f7 -r 41300fa6a67c tools/designer/src/lib/shared/qdesigner_tabwidget.cpp
--- a/tools/designer/src/lib/shared/qdesigner_tabwidget.cpp	Tue Jan 26 12:42:25 2010 +0200
+++ b/tools/designer/src/lib/shared/qdesigner_tabwidget.cpp	Tue Feb 02 00:43:10 2010 +0200
@@ -399,6 +399,7 @@
 static const char *currentTabIconKey = "currentTabIcon";
 static const char *currentTabToolTipKey = "currentTabToolTip";
 static const char *currentTabWhatsThisKey = "currentTabWhatsThis";
+static const char *tabMovableKey = "movable";
 
 QTabWidgetPropertySheet::QTabWidgetPropertySheet(QTabWidget *object, QObject *parent) :
     QDesignerPropertySheet(object, parent),
@@ -411,6 +412,8 @@
         formWindowBase()->addReloadableProperty(this, indexOf(QLatin1String(currentTabIconKey)));
     createFakeProperty(QLatin1String(currentTabToolTipKey), qVariantFromValue(qdesigner_internal::PropertySheetStringValue()));
     createFakeProperty(QLatin1String(currentTabWhatsThisKey), qVariantFromValue(qdesigner_internal::PropertySheetStringValue()));
+    // Prevent the tab widget's drag and drop handling from interfering with Designer's
+    createFakeProperty(QLatin1String(tabMovableKey), QVariant(false));
 }
 
 QTabWidgetPropertySheet::TabWidgetProperty QTabWidgetPropertySheet::tabWidgetPropertyFromName(const QString &name)