10 files changed, 106 insertions, 3 deletions
diff --git a/src/gui/doc/qtgui.qdocconf b/src/gui/doc/qtgui.qdocconf
index e34347b801..027d2663de 100644
--- a/src/gui/doc/qtgui.qdocconf
+++ b/src/gui/doc/qtgui.qdocconf
@@ -33,6 +33,7 @@ depends += \
     qtmultimedia \
     qtnetwork \
     qtopengl \
+    qtplatformheaders \
     qtsvg \
     qtqml \
     qtquick \
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 44fa88e7cf..c5c4f901e0 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -1002,7 +1002,7 @@ QRegion QWindow::mask() const
 /*!
     Requests the window to be activated, i.e. receive keyboard focus.
 
-    \sa isActive(), QGuiApplication::focusWindow()
+    \sa isActive(), QGuiApplication::focusWindow(), QWindowsWindowFunctions::setWindowActivationBehavior()
 */
 void QWindow::requestActivate()
 {
diff --git a/src/platformheaders/doc/qtplatformheaders.qdocconf b/src/platformheaders/doc/qtplatformheaders.qdocconf
index fc8a9d8731..989df524e6 100644
--- a/src/platformheaders/doc/qtplatformheaders.qdocconf
+++ b/src/platformheaders/doc/qtplatformheaders.qdocconf
@@ -27,6 +27,7 @@ qhp.QtPlatformHeaders.subprojects.classes.sortPages = true
 depends += \
     qtcore \
     qtgui \
+    qtwidgets \
     qtdoc
 
 headerdirs  += ..
diff --git a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
index 2b1efcdd6d..d0826bdb50 100644
--- a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
+++ b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
@@ -57,6 +57,11 @@ public:
 
     Q_DECLARE_FLAGS(TouchWindowTouchTypes, TouchWindowTouchType)
 
+    enum WindowActivationBehavior {
+        DefaultActivateWindow,
+        AlwaysActivateWindow
+    };
+
     typedef void (*SetTouchWindowTouchType)(QWindow *window, QWindowsWindowFunctions::TouchWindowTouchTypes touchType);
     static const QByteArray setTouchWindowTouchTypeIdentifier() { return QByteArrayLiteral("WindowsSetTouchWindowTouchType"); }
 
@@ -75,6 +80,16 @@ public:
         if (func)
             func(window, border);
     }
+
+    typedef void (*SetWindowActivationBehaviorType)(WindowActivationBehavior);
+    static const QByteArray setWindowActivationBehaviorIdentifier() { return QByteArrayLiteral("WindowsSetWindowActivationBehavior"); }
+
+    static void setWindowActivationBehavior(WindowActivationBehavior behavior)
+    {
+        SetWindowActivationBehaviorType func = reinterpret_cast<SetWindowActivationBehaviorType>(QGuiApplication::platformFunction(setWindowActivationBehaviorIdentifier()));
+        if (func)
+            func(behavior);
+    }
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QWindowsWindowFunctions::TouchWindowTouchTypes)
diff --git a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
index d6b8764e7b..196f9f22ce 100644
--- a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
+++ b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
@@ -95,3 +95,52 @@
 
     See also \l [QtDoc] {Fullscreen OpenGL Based Windows}
 */
+
+/*!
+    \enum QWindowsWindowFunctions::WindowActivationBehavior
+
+    This enum specifies the behavior of QWidget::activateWindow() and
+    QWindow::requestActivate().
+
+    \value DefaultActivateWindow The window is activated according to the default
+        behavior of the Windows operating system. This means the window will not
+        be activated in some circumstances (most notably when the calling process
+        is not the active process); only the taskbar entry will be flashed.
+    \value AlwaysActivateWindow  The window is always activated, even when the
+        calling process is not the active process.
+
+    \sa QWidget::activateWindow(), QWindow::requestActivate()
+    \since 5.7
+*/
+
+/*!
+    \typedef QWindowsWindowFunctions::SetWindowActivationBehaviorType
+
+    This is the typedef for the function returned by QGuiApplication::platformFunction()
+    when passed setWindowActivationBehaviorIdentifier().
+
+    \sa QWidget::activateWindow(), QWindow::requestActivate()
+    \since 5.7
+*/
+
+/*!
+    \fn QByteArray setWindowActivationBehaviorIdentifier()
+
+    This function returns a bytearray that can be used to query
+    QGuiApplication::platformFunction() to retrieve the SetWindowActivationBehaviorType
+    function.
+
+    \sa QWidget::activateWindow(), QWindow::requestActivate()
+    \since 5.7
+*/
+
+/*!
+    \fn void QWindowsWindowFunctions::setWindowActivationBehavior(WindowActivationBehavior behavior)
+
+    This is a convenience function that can be used directly instead of resolving
+    the function pointer. \a behavior will be relayed to the function retrieved
+    by QGuiApplication.
+
+    \sa QWidget::activateWindow(), QWindow::requestActivate()
+    \since 5.7
+*/
diff --git a/src/plugins/platforms/windows/qwindowsnativeinterface.cpp b/src/plugins/platforms/windows/qwindowsnativeinterface.cpp
index ac7c22fb7e..babca35149 100644
--- a/src/plugins/platforms/windows/qwindowsnativeinterface.cpp
+++ b/src/plugins/platforms/windows/qwindowsnativeinterface.cpp
@@ -84,6 +84,9 @@ static int resourceType(const QByteArray &key)
     return int(result - names);
 }
 
+QWindowsWindowFunctions::WindowActivationBehavior QWindowsNativeInterface::m_windowActivationBehavior =
+    QWindowsWindowFunctions::DefaultActivateWindow;
+
 void *QWindowsNativeInterface::nativeResourceForWindow(const QByteArray &resource, QWindow *window)
 {
     if (!window || !window->handle()) {
@@ -253,6 +256,8 @@ QFunctionPointer QWindowsNativeInterface::platformFunction(const QByteArray &fun
         return QFunctionPointer(QWindowsWindow::setTouchWindowTouchTypeStatic);
     else if (function == QWindowsWindowFunctions::setHasBorderInFullScreenIdentifier())
         return QFunctionPointer(QWindowsWindow::setHasBorderInFullScreenStatic);
+    else if (function == QWindowsWindowFunctions::setWindowActivationBehaviorIdentifier())
+        return QFunctionPointer(QWindowsNativeInterface::setWindowActivationBehavior);
     return Q_NULLPTR;
 }
 
diff --git a/src/plugins/platforms/windows/qwindowsnativeinterface.h b/src/plugins/platforms/windows/qwindowsnativeinterface.h
index 3a0d3398d9..9fc43ddcce 100644
--- a/src/plugins/platforms/windows/qwindowsnativeinterface.h
+++ b/src/plugins/platforms/windows/qwindowsnativeinterface.h
@@ -42,6 +42,7 @@
 
 #include <QtGui/qfont.h>
 #include <QtGui/qpa/qplatformnativeinterface.h>
+#include <QtPlatformHeaders/qwindowswindowfunctions.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -96,7 +97,15 @@ public:
     QVariant windowProperty(QPlatformWindow *window, const QString &name, const QVariant &defaultValue) const Q_DECL_OVERRIDE;
     void setWindowProperty(QPlatformWindow *window, const QString &name, const QVariant &value) Q_DECL_OVERRIDE;
 
+    static QWindowsWindowFunctions::WindowActivationBehavior windowActivationBehavior()
+        { return QWindowsNativeInterface::m_windowActivationBehavior; }
+    static void setWindowActivationBehavior(QWindowsWindowFunctions::WindowActivationBehavior b)
+        { QWindowsNativeInterface::m_windowActivationBehavior = b; }
+
     QFunctionPointer platformFunction(const QByteArray &function) const Q_DECL_OVERRIDE;
+
+private:
+    static QWindowsWindowFunctions::WindowActivationBehavior m_windowActivationBehavior;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 4c503a2c48..c1a047e276 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -43,6 +43,7 @@
 #include "qwindowsdrag.h"
 #include "qwindowsscreen.h"
 #include "qwindowsintegration.h"
+#include "qwindowsnativeinterface.h"
 #include "qwindowsopenglcontext.h"
 #ifdef QT_NO_CURSOR
 #  include "qwindowscursor.h"
@@ -2083,8 +2084,30 @@ void QWindowsWindow::requestActivateWindow()
     // 'Active' state handling is based in focus since it needs to work for
     // child windows as well.
     if (m_data.hwnd) {
+#ifndef Q_OS_WINCE
+        const DWORD currentThread = GetCurrentThreadId();
+        bool attached = false;
+        DWORD foregroundThread = 0;
+
+        // QTBUG-14062, QTBUG-37435: Windows normally only flashes the taskbar entry
+        // when activating windows of inactive applications. Attach to the input of the
+        // currently active window while setting the foreground window to always activate
+        // the window when desired.
+        if (QGuiApplication::applicationState() != Qt::ApplicationActive
+            && QWindowsNativeInterface::windowActivationBehavior() == QWindowsWindowFunctions::AlwaysActivateWindow) {
+            if (const HWND foregroundWindow = GetForegroundWindow()) {
+                foregroundThread = GetWindowThreadProcessId(foregroundWindow, NULL);
+                if (foregroundThread && foregroundThread != currentThread)
+                    attached = AttachThreadInput(foregroundThread, currentThread, TRUE) == TRUE;
+            }
+        }
+#endif // !Q_OS_WINCE
         SetForegroundWindow(m_data.hwnd);
         SetFocus(m_data.hwnd);
+#ifndef Q_OS_WINCE
+        if (attached)
+            AttachThreadInput(foregroundThread, currentThread, FALSE);
+#endif // !Q_OS_WINCE
     }
 }
 
diff --git a/src/widgets/doc/qtwidgets.qdocconf b/src/widgets/doc/qtwidgets.qdocconf
index 8160396ca2..75bbb99579 100644
--- a/src/widgets/doc/qtwidgets.qdocconf
+++ b/src/widgets/doc/qtwidgets.qdocconf
@@ -26,7 +26,7 @@ qhp.QtWidgets.subprojects.classes.sortPages = true
 
 tagfile                 = ../../../doc/qtwidgets/qtwidgets.tags
 
-depends                 += qtcore qtgui qtdoc qtsql qtdesigner qtquick qmake qtsvg
+depends                 += qtcore qtgui qtdoc qtsql qtdesigner qtquick qmake qtplatformheaders qtsvg
 
 headerdirs  += ..
 
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 7e2e02b58e..de832d667d 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -12689,7 +12689,7 @@ QWidget *QWidget::keyboardGrabber()
     does not allow an application to interrupt what the user is currently
     doing in another application.
 
-    \sa isActiveWindow(), window(), show()
+    \sa isActiveWindow(), window(), show(), QWindowsWindowFunctions::setWindowActivationBehavior()
 */
 void QWidget::activateWindow()
 {