Fix title bar height of Aero wizard on Windows 8.

Windows 8 no longer allows for negative values to WM_NCCALCSIZE
to shrink the title bar.

Task-number: QTBUG-28435
Change-Id: Ib6aa95a98663c4dc8e9a18407b5d49a0daeab8f9
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
(cherry picked from qtbase/5fb6331a17a5c43b91daddf4a30e46ccbd1419b5)

2 files changed, 23 insertions, 9 deletions

diff --git a/src/gui/dialogs/qwizard_win.cpp b/src/gui/dialogs/qwizard_win.cpp
index 303a1c6aba..67141f6cc4 100644
--- a/src/gui/dialogs/qwizard_win.cpp
+++ b/src/gui/dialogs/qwizard_win.cpp
@@ -390,12 +390,15 @@ bool QVistaHelper::winEvent(MSG* msg, long* result)
         }
         break;
     }
-    case WM_NCCALCSIZE: {
-        NCCALCSIZE_PARAMS* lpncsp = (NCCALCSIZE_PARAMS*)msg->lParam;
-        *result = DefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam);
-        lpncsp->rgrc[0].top -= (vistaState() == VistaAero ? titleBarSize() : 0);
+    case WM_NCCALCSIZE:
+        if (QSysInfo::WindowsVersion < QSysInfo::WV_WINDOWS8 && vistaState() == VistaAero) {
+            NCCALCSIZE_PARAMS* lpncsp = (NCCALCSIZE_PARAMS*)msg->lParam;
+            *result = DefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam);
+            lpncsp->rgrc[0].top -= titleBarSize();
+        } else {
+            return false; // Negative margins no longer work on Windows 8.
+        }
         break;
-    }
     default:
         LRESULT lResult;
         // Pass to DWM to handle
@@ -767,6 +770,19 @@ int QVistaHelper::titleOffset()
     return leftMargin() + iconOffset;
 }
 
+int QVistaHelper::topOffset()
+{
+    if (vistaState() != VistaAero)
+        return titleBarSize() + 3;
+    static const int aeroOffset =
+        QSysInfo::WindowsVersion == QSysInfo::WV_WINDOWS7 ?
+        QStyleHelper::dpiScaled(4) : QStyleHelper::dpiScaled(13);
+    int result = aeroOffset;
+    if (QSysInfo::WindowsVersion < QSysInfo::WV_WINDOWS8)
+        result += titleBarSize();
+    return result;
+}
+
 QT_END_NAMESPACE
 
 #endif // QT_NO_STYLE_WINDOWSVISTA
diff --git a/src/gui/dialogs/qwizard_win_p.h b/src/gui/dialogs/qwizard_win_p.h
index e4818a24f0..3043c9cdca 100644
--- a/src/gui/dialogs/qwizard_win_p.h
+++ b/src/gui/dialogs/qwizard_win_p.h
@@ -105,10 +105,8 @@ public:
         return int(QStyleHelper::dpiScaled(
                 QSysInfo::WindowsVersion >= QSysInfo::WV_WINDOWS7 ? 4 : 6));
     }
-    static int topOffset() {
-        static int aeroOffset = QSysInfo::WindowsVersion >= QSysInfo::WV_WINDOWS7 ?
-                                QStyleHelper::dpiScaled(4) : QStyleHelper::dpiScaled(13);
-        return (titleBarSize() + (vistaState() == VistaAero ? aeroOffset : 3)); }
+    static int topOffset();
+
 private:
     static HFONT getCaptionFont(HANDLE hTheme);
     bool drawTitleText(QPainter *painter, const QString &text, const QRect &rect, HDC hdc);