3 files changed, 35 insertions, 34 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index 3f4555a31f..872fd07729 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -842,9 +842,6 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
     case QtWindows::FocusOutEvent:
         handleFocusEvent(et, platformWindow);
         return true;
-    case QtWindows::ShowEvent:
-        platformWindow->handleShown();
-        return false; // Indicate transient children should be shown by windows (SW_PARENTOPENING)
     case QtWindows::HideEvent:
         platformWindow->handleHidden();
         return false;// Indicate transient children should be hidden by windows (SW_PARENTCLOSING)
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 9a9877b43f..1ff98a3d29 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -839,6 +839,15 @@ QWindowsWindow::~QWindowsWindow()
     destroyIcon();
 }
 
+void QWindowsWindow::fireExpose(const QRegion &region, bool force)
+{
+    if (region.isEmpty() && !force)
+        clearFlag(Exposed);
+    else
+        setFlag(Exposed);
+    QWindowSystemInterface::handleExposeEvent(window(), region);
+}
+
 void QWindowsWindow::destroyWindow()
 {
     if (QWindowsContext::verboseIntegration || QWindowsContext::verboseWindows)
@@ -942,13 +951,19 @@ void QWindowsWindow::setVisible(bool visible)
     if (m_data.hwnd) {
         if (visible) {
             show_sys();
-            QWindowSystemInterface::handleExposeEvent(window(),
-                                                      QRect(QPoint(), geometry().size()));
+
+            // When the window is layered, we won't get WM_PAINT, and "we" are in control
+            // over the rendering of the window
+            // There is nobody waiting for this, so we don't need to flush afterwards.
+            QWindow *w = window();
+            if (w->format().hasAlpha() || qFuzzyCompare(w->opacity(), qreal(1)))
+                fireExpose(QRect(0, 0, w->width(), w->height()));
+
         } else {
             if (hasMouseCapture())
                 setMouseGrabEnabled(false);
             hide_sys();
-            QWindowSystemInterface::handleExposeEvent(window(), QRegion());
+            fireExpose(QRegion());
         }
     }
 }
@@ -1094,14 +1109,9 @@ void QWindowsWindow::setParent_sys(const QPlatformWindow *parent) const
     }
 }
 
-void QWindowsWindow::handleShown()
-{
-    QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), geometry().size()));
-}
-
 void QWindowsWindow::handleHidden()
 {
-    QWindowSystemInterface::handleExposeEvent(window(), QRegion());
+    fireExpose(QRegion());
 }
 
 void QWindowsWindow::setGeometry(const QRect &rectIn)
@@ -1267,28 +1277,21 @@ bool QWindowsWindow::handleWmPaint(HWND hwnd, UINT message,
     if (message == WM_ERASEBKGND) // Backing store - ignored.
         return true;
     PAINTSTRUCT ps;
-    if (testFlag(OpenGLSurface)) {
-        // Observed painting problems with Aero style disabled (QTBUG-7865).
-        if (testFlag(OpenGLDoubleBuffered))
-            InvalidateRect(hwnd, 0, false);
-        BeginPaint(hwnd, &ps);
-        QWindowSystemInterface::handleExposeEvent(window(), QRegion(qrectFromRECT(ps.rcPaint)));
-        if (!QWindowsContext::instance()->asyncExpose())
-            QWindowSystemInterface::flushWindowSystemEvents();
 
-        EndPaint(hwnd, &ps);
-    } else {
-        BeginPaint(hwnd, &ps);
-        const QRect updateRect = qrectFromRECT(ps.rcPaint);
+    // Observed painting problems with Aero style disabled (QTBUG-7865).
+    if (testFlag(OpenGLSurface) && testFlag(OpenGLDoubleBuffered))
+        InvalidateRect(hwnd, 0, false);
 
-        if (QWindowsContext::verboseIntegration)
-            qDebug() << __FUNCTION__ << this << window() << updateRect;
+    BeginPaint(hwnd, &ps);
 
-        QWindowSystemInterface::handleExposeEvent(window(), QRegion(updateRect));
-        if (!QWindowsContext::instance()->asyncExpose())
-            QWindowSystemInterface::flushWindowSystemEvents();
-        EndPaint(hwnd, &ps);
-    }
+    // If the a window is obscured by another window (such as a child window)
+    // we still need to send isExposed=true, for compatibility.
+    // Our tests depend on it.
+    fireExpose(QRegion(qrectFromRECT(ps.rcPaint)), true);
+    if (!QWindowsContext::instance()->asyncExpose())
+        QWindowSystemInterface::flushWindowSystemEvents();
+
+    EndPaint(hwnd, &ps);
     return true;
 }
 
diff --git a/src/plugins/platforms/windows/qwindowswindow.h b/src/plugins/platforms/windows/qwindowswindow.h
index 2117ca50b8..fed9d089df 100644
--- a/src/plugins/platforms/windows/qwindowswindow.h
+++ b/src/plugins/platforms/windows/qwindowswindow.h
@@ -133,7 +133,8 @@ public:
         WithinSetStyle = 0x800,
         WithinDestroy = 0x1000,
         TouchRegistered = 0x2000,
-        AlertState = 0x4000
+        AlertState = 0x4000,
+        Exposed = 0x08000
     };
 
     struct WindowData
@@ -161,7 +162,7 @@ public:
 
     virtual void setVisible(bool visible);
     bool isVisible() const;
-    virtual bool isExposed() const { return m_windowState != Qt::WindowMinimized && isVisible(); }
+    virtual bool isExposed() const { return testFlag(Exposed); }
     virtual bool isActive() const;
     virtual bool isEmbedded(const QPlatformWindow *parentWindow) const;
     virtual QPoint mapToGlobal(const QPoint &pos) const;
@@ -217,7 +218,6 @@ public:
 
     void handleMoved();
     void handleResized(int wParam);
-    void handleShown();
     void handleHidden();
 
     static inline HWND handleOf(const QWindow *w);
@@ -278,6 +278,7 @@ private:
     void handleGeometryChange();
     void handleWindowStateChange(Qt::WindowState state);
     inline void destroyIcon();
+    void fireExpose(const QRegion &region, bool force=false);
 
     mutable WindowData m_data;
     mutable unsigned m_flags;