diff -urN qt-win-commercial-src-4.5.1.orig/src/gui/kernel/qwidget_win.cpp qt-win-commercial-src-4.5.1/src/gui/kernel/qwidget_win.cpp
--- qt-win-commercial-src-4.5.1.orig/src/gui/kernel/qwidget_win.cpp	2009-04-22 02:01:56.000000000 +0400
+++ qt-win-commercial-src-4.5.1/src/gui/kernel/qwidget_win.cpp	2009-04-29 19:15:38.000000000 +0400
@@ -363,6 +363,10 @@
             } else {
                  exsty |= WS_EX_TOOLWINDOW;
             }
+
+            if (q->property("is-appwindow").toBool()) {
+                 exsty |= WS_EX_APPWINDOW;
+            }
         }
     }