QWizard/Win: Handle hit testing correctly for Vista style

Clicking the area just below the close button when Aero is enabled
reveals duplicate caption buttons. DwmDefWindowProc returns hit results
for DWM caption buttons but DefWindowProc may also return hit results
for non-DWM caption buttons.

To resolve this issue, if DefWindowProc returns a window button hit
result then we just use HTCLIENT (the client area) as the hit result
instead.

Change-Id: Ia741ce4f9aa944109d8de54c2f84009f5ea1883f
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

1 files changed, 50 insertions, 39 deletions

diff --git a/src/widgets/dialogs/qwizard_win.cpp b/src/widgets/dialogs/qwizard_win.cpp
index 6c24231a88..6359ebfb09 100644
--- a/src/widgets/dialogs/qwizard_win.cpp
+++ b/src/widgets/dialogs/qwizard_win.cpp
@@ -378,25 +378,24 @@ void QVistaHelper::setTitleBarIconAndCaptionVisible(bool visible)
 
 bool QVistaHelper::winEvent(MSG* msg, long* result)
 {
-    bool retval = true;
-
     switch (msg->message) {
     case WM_NCHITTEST: {
         LRESULT lResult;
-        pDwmDefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam, &lResult);
-        if (lResult == HTCLOSE || lResult == HTMAXBUTTON || lResult == HTMINBUTTON || lResult == HTHELP)
+        // Perform hit testing using DWM
+        if (pDwmDefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam, &lResult)) {
+            // DWM returned a hit, no further processing necessary
             *result = lResult;
-        else
-            *result = DefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam);
-        break;
-    }
-    case WM_NCMOUSEMOVE:
-    case WM_NCLBUTTONDOWN:
-    case WM_NCLBUTTONUP:
-    case WIZ_WM_NCMOUSELEAVE: {
-        LRESULT lResult;
-        pDwmDefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam, &lResult);
-        *result = DefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam);
+        } else {
+            // DWM didn't return a hit, process using DefWindowProc
+            lResult = DefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam);
+            // If DefWindowProc returns a window caption button, just return HTCLIENT (client area).
+            // This avoid unnecessary hits to Windows NT style caption buttons which aren't visible but are
+            // located just under the Aero style window close button.
+            if (lResult == HTCLOSE || lResult == HTMAXBUTTON || lResult == HTMINBUTTON || lResult == HTHELP)
+                *result = HTCLIENT;
+            else
+                *result = lResult;
+        }
         break;
     }
 //    case WM_NCCALCSIZE: { #fixme: If the frame size is changed, it needs to be communicated to the QWindow.
@@ -407,10 +406,16 @@ bool QVistaHelper::winEvent(MSG* msg, long* result)
 //        break;
 //    }
     default:
-        retval = false;
+        LRESULT lResult;
+        // Pass to DWM to handle
+        if (pDwmDefWindowProc(msg->hwnd, msg->message, msg->wParam, msg->lParam, &lResult))
+            *result = lResult;
+        // If the message wasn't handled by DWM, continue processing it as normal
+        else
+            return false;
     }
 
-    return retval;
+    return true;
 }
 
 void QVistaHelper::setMouseCursor(QPoint pos)
@@ -597,30 +602,36 @@ bool QVistaHelper::eventFilter(QObject *obj, QEvent *event)
         winEvent(&msg, &result);
      } else if (event->type() == QEvent::MouseButtonPress) {
         QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
-        long result;
-        MSG msg;
-        msg.message = WM_NCHITTEST;
-        msg.wParam  = 0;
-        msg.lParam = MAKELPARAM(mouseEvent->globalX(), mouseEvent->globalY());
-        HWND handle = QApplicationPrivate::getHWNDForWidget(wizard);
-        msg.hwnd = handle;
-        winEvent(&msg, &result);
-        msg.wParam = result;
-        msg.message = WM_NCLBUTTONDOWN;
-        winEvent(&msg, &result);
+
+        if (mouseEvent->button() == Qt::LeftButton) {
+            long result;
+            MSG msg;
+            msg.message = WM_NCHITTEST;
+            msg.wParam  = 0;
+            msg.lParam = MAKELPARAM(mouseEvent->globalX(), mouseEvent->globalY());
+            HWND handle = QApplicationPrivate::getHWNDForWidget(wizard);
+            msg.hwnd = handle;
+            winEvent(&msg, &result);
+            msg.wParam = result;
+            msg.message = WM_NCLBUTTONDOWN;
+            winEvent(&msg, &result);
+        }
      } else if (event->type() == QEvent::MouseButtonRelease) {
         QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
-        long result;
-        MSG msg;
-        msg.message = WM_NCHITTEST;
-        msg.wParam  = 0;
-        msg.lParam = MAKELPARAM(mouseEvent->globalX(), mouseEvent->globalY());
-        HWND handle = QApplicationPrivate::getHWNDForWidget(wizard);
-        msg.hwnd = handle;
-        winEvent(&msg, &result);
-        msg.wParam = result;
-        msg.message = WM_NCLBUTTONUP;
-        winEvent(&msg, &result);
+
+        if (mouseEvent->button() == Qt::LeftButton) {
+            long result;
+            MSG msg;
+            msg.message = WM_NCHITTEST;
+            msg.wParam  = 0;
+            msg.lParam = MAKELPARAM(mouseEvent->globalX(), mouseEvent->globalY());
+            HWND handle = QApplicationPrivate::getHWNDForWidget(wizard);
+            msg.hwnd = handle;
+            winEvent(&msg, &result);
+            msg.wParam = result;
+            msg.message = WM_NCLBUTTONUP;
+            winEvent(&msg, &result);
+        }
      }
 
      return false;