Fix wheel events in Windows

Wheel events were always passed to window that got them from native
message loop, which isn't what Qt expects. Changed the receiver to
preferably be the window under cursor, as long as it is not blocked by
modal window.

Change-Id: I4edf0608842fe5b822a7f574abfdae81fa755ee5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 2f7058ab97..955617e399 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -783,10 +783,26 @@ void QWindowsWindow::unregisterDropSite()
     }
 }
 
+// Returns topmost QWindowsWindow ancestor even if there are embedded windows in the chain.
+// Returns this window if it is the topmost ancestor.
 QWindow *QWindowsWindow::topLevelOf(QWindow *w)
 {
     while (QWindow *parent = w->parent())
         w = parent;
+
+    const QWindowsWindow *ww = static_cast<const QWindowsWindow *>(w->handle());
+
+    // In case the topmost parent is embedded, find next ancestor using native methods
+    if (ww->isEmbedded(0)) {
+        HWND parentHWND = GetAncestor(ww->handle(), GA_PARENT);
+        const HWND desktopHwnd = GetDesktopWindow();
+        const QWindowsContext *ctx = QWindowsContext::instance();
+        while (parentHWND && parentHWND != desktopHwnd) {
+            if (QWindowsWindow *ancestor = ctx->findPlatformWindow(parentHWND))
+                return topLevelOf(ancestor->window());
+            parentHWND = GetAncestor(parentHWND, GA_PARENT);
+        }
+    }
     return w;
 }