1 files changed, 17 insertions, 8 deletions

diff --git a/src/gui/kernel/qapplication_win.cpp b/src/gui/kernel/qapplication_win.cpp
index 1af45ba..6f5aa11 100644
--- a/src/gui/kernel/qapplication_win.cpp
+++ b/src/gui/kernel/qapplication_win.cpp
@@ -942,29 +942,36 @@ bool qt_nograb()                                // application no-grab option
 typedef QHash<QString, int> WinClassNameHash;
 Q_GLOBAL_STATIC(WinClassNameHash, winclassNames)
 
+//
+// If 0 is passed as the widget pointer, register a window class
+// for QWidget as default. This is used in QGLTemporaryContext
+// during GL initialization, where we don't want to use temporary
+// QWidgets or QGLWidgets, neither do we want to have separate code
+// to register window classes.
+//
 const QString qt_reg_winclass(QWidget *w)        // register window class
 {
-    int flags = w->windowFlags();
+    int flags = w ? w->windowFlags() : 0;
     int type = flags & Qt::WindowType_Mask;
 
     uint style;
     bool icon;
     QString cname;
-    if (qt_widget_private(w)->isGLWidget) {
+    if (w && qt_widget_private(w)->isGLWidget) {
         cname = QLatin1String("QGLWidget");
         style = CS_DBLCLKS;
 #ifndef Q_WS_WINCE
         style |= CS_OWNDC;
 #endif
         icon  = true;
-    } else if (flags & Qt::MSWindowsOwnDC) {
+    } else if (w && (flags & Qt::MSWindowsOwnDC)) {
         cname = QLatin1String("QWidgetOwnDC");
         style = CS_DBLCLKS;
 #ifndef Q_WS_WINCE
         style |= CS_OWNDC;
 #endif
         icon  = true;
-    } else if (type == Qt::Tool || type == Qt::ToolTip){
+    } else if (w && (type == Qt::Tool || type == Qt::ToolTip)) {
         style = CS_DBLCLKS;
         if (w->inherits("QTipLabel") || w->inherits("QAlphaWidget")) {
             if ((QSysInfo::WindowsVersion >= QSysInfo::WV_XP
@@ -979,7 +986,7 @@ const QString qt_reg_winclass(QWidget *w)        // register window class
         style |= CS_SAVEBITS;
 #endif
         icon = false;
-    } else if (type == Qt::Popup) {
+    } else if (w && (type == Qt::Popup)) {
         cname = QLatin1String("QPopup");
         style = CS_DBLCLKS;
 #ifndef Q_WS_WINCE
@@ -1050,7 +1057,10 @@ const QString qt_reg_winclass(QWidget *w)        // register window class
     }
     wc.hCursor      = 0;
 #ifndef Q_WS_WINCE
-    wc.hbrBackground = qt_widget_private(w)->isGLWidget ? 0 : (HBRUSH)GetSysColorBrush(COLOR_WINDOW);
+    HBRUSH brush = 0;
+    if (w && !qt_widget_private(w)->isGLWidget)
+        brush = (HBRUSH)GetSysColorBrush(COLOR_WINDOW);
+    wc.hbrBackground = brush;
 #else
     wc.hbrBackground = 0;
 #endif
@@ -1072,8 +1082,7 @@ const QString qt_reg_winclass(QWidget *w)        // register window class
 
 Q_GUI_EXPORT const QString qt_getRegisteredWndClass()
 {
-    QWidget w;
-    return qt_reg_winclass(&w);
+    return qt_reg_winclass(0);
 }
 
 static void unregWinClasses()