QPlatformDialogHelper: Split class hierarchy, decouple from Dialog

- Introduce hierarchy of QPlatformDialogHelper-derived classes
  for font, color and file dialogs.
- Start reducing dependencies on QDialog:
  * Remove QDialog-specifics from interface, introduce enumeration
    for DialogCode
  * Make the helpers Q_OBJECTS to be able to add the signals
    passed on to the QDialogs
  * Remove QDialogPrivate pointer
- Split setVisible_sys() in show_sys() (factory method for native
  dialogs) and hide_sys(). Pass parent window to  show_sys(),
  removing the necessity to query the QDialog for it
- Introduce a styleHint() similar to QGuiApplication's for
  platform-specific
- Fix compile in cocoa/windows, reduce depency on QDialog
  (-private) classes.

Change-Id: Ic1cb715e1edf767f2cb18b9780341d189339ef1d
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>

15 files changed, 366 insertions, 199 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.h b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.h
index 06309ab62b..c38ea90f19 100644
--- a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.h
+++ b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.h
@@ -44,10 +44,11 @@
 
 #include <QObject>
 #include <qplatformdialoghelper_qpa.h>
+
 class QFileDialog;
 class QFileDialogPrivate;
 
-class QCocoaFileDialogHelper : public QPlatformDialogHelper
+class QCocoaFileDialogHelper : public QPlatformFileDialogHelper
 {
 public:
     QCocoaFileDialogHelper(QFileDialog *dialog);
@@ -59,8 +60,9 @@ public:
     bool defaultNameFilterDisables() const;
 
     void deleteNativeDialog_sys();
-    bool setVisible_sys(bool visible);
-    QDialog::DialogCode dialogResultCode_sys();
+    bool show_sys(QWindow *parent);
+    void hide_sys();
+    QPlatformFileDialogHelper::DialogCode dialogResultCode_sys();
     void setDirectory_sys(const QString &directory);
     QString directory_sys() const;
     void selectFile_sys(const QString &filename);
diff --git a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
index bdccf5dfa5..820a5dcbd0 100644
--- a/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
+++ b/src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm
@@ -89,7 +89,7 @@ QT_USE_NAMESPACE
     NSView *mAccessoryView;
     NSPopUpButton *mPopUpButton;
     NSTextField *mTextField;
-    QFileDialogPrivate *mPriv;
+    QFileDialog *mFileDialog;
     QCocoaFileDialogHelper *mHelper;
     NSString *mCurrentDir;
     bool mConfirmOverwrite;
@@ -133,11 +133,11 @@ QT_USE_NAMESPACE
     fileMode:(QT_PREPEND_NAMESPACE(QFileDialog::FileMode))fileMode
     selectFile:(const QString &)selectFile
     confirmOverwrite:(bool)confirm
-    priv:(QFileDialogPrivate *)priv
+    fileDialog:(QFileDialog *)fileDialog
     helper:(QCocoaFileDialogHelper *)helper
 {
     self = [super init];
-
+    mFileDialog = fileDialog;
     mAcceptMode = acceptMode;
     if (mAcceptMode == QT_PREPEND_NAMESPACE(QFileDialog::AcceptOpen)){
         mOpenPanel = [NSOpenPanel openPanel];
@@ -154,12 +154,11 @@ QT_USE_NAMESPACE
     mFileMode = fileMode;
     mConfirmOverwrite = confirm;
     mReturnCode = -1;
-    mPriv = priv;
     mHelper = helper;
     mLastFilterCheckPath = new QString;
     mQDirFilterEntryList = new QStringList;
-    mNameFilterDropDownList = new QStringList(priv->nameFilters);
-    QString selectedVisualNameFilter = priv->qFileDialogUi->fileTypeCombo->currentText();
+    mNameFilterDropDownList = new QStringList(mFileDialog->nameFilters());
+    QString selectedVisualNameFilter = mFileDialog->selectedNameFilter();
     mSelectedNameFilter = new QStringList([self findStrippedFilterWithVisualFilterName:selectedVisualNameFilter]);
 
     QFileInfo sel(selectFile);
@@ -177,11 +176,10 @@ QT_USE_NAMESPACE
     [self createAccessory];
     [mSavePanel setAccessoryView:mNameFilterDropDownList->size() > 1 ? mAccessoryView : nil];
 
-    if (mPriv){
-        [mSavePanel setPrompt:[self strip:mPriv->acceptLabel]];
-        if (mPriv->fileNameLabelExplicitlySat)
-            [mSavePanel setNameFieldLabel:[self strip:mPriv->qFileDialogUi->fileNameLabel->text()]];
-    }
+
+    [mSavePanel setPrompt:[self strip:mFileDialog->labelText(QFileDialog::Accept)]];
+    if (false) // ### fixme mPriv->fileNameLabelExplicitlySat)
+        [mSavePanel setNameFieldLabel:[self strip:mFileDialog->labelText(QFileDialog::FileName)]];
 
     [self updateProperties];
     [mSavePanel retain];
@@ -254,9 +252,9 @@ QT_USE_NAMESPACE
     return (mReturnCode == NSOKButton);
 }
 
-- (QT_PREPEND_NAMESPACE(QDialog::DialogCode))dialogResultCode
+- (QT_PREPEND_NAMESPACE(QPlatformDialogHelper::DialogCode))dialogResultCode
 {
-    return (mReturnCode == NSOKButton) ? QT_PREPEND_NAMESPACE(QDialog::Accepted) : QT_PREPEND_NAMESPACE(QDialog::Rejected);
+    return (mReturnCode == NSOKButton) ? QT_PREPEND_NAMESPACE(QPlatformDialogHelper::Accepted) : QT_PREPEND_NAMESPACE(QPlatformDialogHelper::Rejected);
 }
 
 - (void)showWindowModalSheet:(QWidget *)docWidget
@@ -391,8 +389,9 @@ QT_USE_NAMESPACE
     [mOpenPanel setResolvesAliases:!(*mFileOptions & QT_PREPEND_NAMESPACE(QFileDialog::DontResolveSymlinks))];
 
     QStringList ext = [self acceptableExtensionsForSave];
-    if (mPriv && !ext.isEmpty() && !mPriv->defaultSuffix.isEmpty())
-        ext.prepend(mPriv->defaultSuffix);
+    const QString defaultSuffix = mFileDialog->defaultSuffix();
+    if (!ext.isEmpty() && !defaultSuffix.isEmpty())
+        ext.prepend(defaultSuffix);
     [mSavePanel setAllowedFileTypes:ext.isEmpty() ? nil : QT_PREPEND_NAMESPACE(qt_mac_QStringListToNSMutableArray(ext))];
 
     if ([mSavePanel isVisible])
@@ -474,10 +473,7 @@ QT_USE_NAMESPACE
     [mTextField setSelectable:false];
     [mTextField setBordered:false];
     [mTextField setDrawsBackground:false];
-    if (mPriv){
-        [mTextField setStringValue:[self strip:mPriv->qFileDialogUi->fileTypeLabel->text()]];
-    } else
-        [mTextField setStringValue:QT_PREPEND_NAMESPACE(qt_mac_QStringToNSString)(QT_PREPEND_NAMESPACE(QFileDialog::tr)("Files of type:"))];
+    [mTextField setStringValue:[self strip:mFileDialog->labelText(QFileDialog::FileType)]];
 }
 
 - (void)createPopUpButton:(const QString &)selectedFilter hideDetails:(BOOL)hideDetails
@@ -555,15 +551,14 @@ void QCocoaFileDialogHelper::QNSOpenSavePanelDelegate_panelClosed(bool accepted)
 
 void QCocoaFileDialogHelper::QNSOpenSavePanelDelegate_directoryEntered(const QString &newDir)
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
-    priv->setLastVisitedDirectory(newDir);
-    qtFileDialog->metaObject()->invokeMethod(qtFileDialog, "directoryEntered", Q_ARG(QString, newDir));
+    // ### fixme: priv->setLastVisitedDirectory(newDir);
+    emit directoryEntered(newDir);
 }
 
 void QCocoaFileDialogHelper::QNSOpenSavePanelDelegate_filterSelected(int menuIndex)
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
-    qtFileDialog->metaObject()->invokeMethod(qtFileDialog, "filterSelected", Q_ARG(QString, priv->nameFilters.at(menuIndex)));
+    const QStringList filters = qtFileDialog->nameFilters();
+    emit filterSelected(menuIndex >= 0 && menuIndex < filters.size() ? filters.at(menuIndex) : QString());
 }
 
 extern OSErr qt_mac_create_fsref(const QString &, FSRef *); // qglobal.cpp
@@ -607,22 +602,20 @@ void QCocoaFileDialogHelper::setNameFilters_sys(const QStringList &filters)
 
 void QCocoaFileDialogHelper::setFilter_sys()
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
     QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = static_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate);
-    *(delegate->mQDirFilter) = priv->model->filter();
-    delegate->mFileMode = priv->fileMode;
+    *(delegate->mQDirFilter) = qtFileDialog->filter();
+    delegate->mFileMode = qtFileDialog->fileMode();
     [delegate->mSavePanel setTitle:qt_mac_QStringToNSString(qtFileDialog->windowTitle())];
-    [delegate->mSavePanel setPrompt:[delegate strip:priv->acceptLabel]];
-    if (priv->fileNameLabelExplicitlySat)
-        [delegate->mSavePanel setNameFieldLabel:[delegate strip:priv->qFileDialogUi->fileNameLabel->text()]];
+    [delegate->mSavePanel setPrompt:[delegate strip:qtFileDialog->labelText(QFileDialog::Accept)]];
+    if (false) // ### fixme priv->fileNameLabelExplicitlySat)
+        [delegate->mSavePanel setNameFieldLabel:[delegate strip:qtFileDialog->labelText(QFileDialog::FileName)]];
 
     [delegate updateProperties];
 }
 
 void QCocoaFileDialogHelper::selectNameFilter_sys(const QString &filter)
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
-    int index = priv->nameFilters.indexOf(filter);
+    const int index = qtFileDialog->nameFilters().indexOf(filter);
     if (index != -1) {
         QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = static_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate);
         [delegate->mPopUpButton selectItemAtIndex:index];
@@ -632,24 +625,27 @@ void QCocoaFileDialogHelper::selectNameFilter_sys(const QString &filter)
 
 QString QCocoaFileDialogHelper::selectedNameFilter_sys() const
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
     QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = static_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate);
     int index = [delegate->mPopUpButton indexOfSelectedItem];
-    return index != -1 ? priv->nameFilters.at(index) : QString();
+    return index != -1 ? qtFileDialog->nameFilters().at(index) : QString();
 }
 
 void QCocoaFileDialogHelper::deleteNativeDialog_sys()
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
     [reinterpret_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate) release];
     mDelegate = 0;
-    priv->nativeDialogInUse = false;
 }
 
-bool QCocoaFileDialogHelper::setVisible_sys(bool visible)
+void QCocoaFileDialogHelper::hide_sys()
+{
+    if (!qtFileDialog->isHidden())
+        hideCocoaFilePanel();
+}
+
+bool QCocoaFileDialogHelper::show_sys(QWindow * /* parent */)
 {
 //    Q_Q(QFileDialog);
-    if (!visible == qtFileDialog->isHidden())
+    if (!qtFileDialog->isHidden())
         return false;
 
     if (qtFileDialog->windowFlags() & Qt::WindowStaysOnTopHint) {
@@ -660,27 +656,26 @@ bool QCocoaFileDialogHelper::setVisible_sys(bool visible)
         return false;
     }
 
-    return visible ? showCocoaFilePanel() : hideCocoaFilePanel();
+    return showCocoaFilePanel();
 }
 
 void QCocoaFileDialogHelper::createNSOpenSavePanelDelegate()
 {
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
     if (mDelegate)
         return;
 
     bool selectDir = qtFileDialog->selectedFiles().isEmpty();
     QString selection(selectDir ? qtFileDialog->directory().absolutePath() : qtFileDialog->selectedFiles().value(0));
     QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = [[QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) alloc]
-        initWithAcceptMode:priv->acceptMode
+        initWithAcceptMode:qtFileDialog->acceptMode()
         title:qtFileDialog->windowTitle()
         hideNameFilterDetails:qtFileDialog->testOption(QFileDialog::HideNameFilterDetails)
-        qDirFilter:priv->model->filter()
-        fileOptions:priv->opts
-        fileMode:priv->fileMode
+        qDirFilter:qtFileDialog->filter()
+        fileOptions:qtFileDialog->options()
+        fileMode:qtFileDialog->fileMode()
         selectFile:selection
         confirmOverwrite:!qtFileDialog->testOption(QFileDialog::DontConfirmOverwrite)
-        priv:priv
+        fileDialog:qtFileDialog
         helper:this];
 
     mDelegate = delegate;
@@ -722,10 +717,7 @@ void QCocoaFileDialogHelper::platformNativeDialogModalHelp()
     // running (which is the case if e.g a top-most QEventLoop has been
     // interrupted, and the second-most event loop has not yet been reactivated (regardless
     // if [NSApp run] is still on the stack)), showing a native modal dialog will fail.
-    QFileDialogPrivate *priv = static_cast<QFileDialogPrivate*>(d_ptr);
-    if (priv->nativeDialogInUse){
-        QTimer::singleShot(1, qtFileDialog, SLOT(_q_platformRunNativeAppModalPanel()));
-    }
+    QTimer::singleShot(1, qtFileDialog, SLOT(_q_platformRunNativeAppModalPanel()));
 }
 
 void QCocoaFileDialogHelper::_q_platformRunNativeAppModalPanel()
@@ -736,13 +728,13 @@ void QCocoaFileDialogHelper::_q_platformRunNativeAppModalPanel()
 #endif
     QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = static_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate);
     [delegate runApplicationModalPanel];
-    if (dialogResultCode_sys() == QDialog::Accepted)
+    if (dialogResultCode_sys() == QPlatformDialogHelper::Accepted)
         qtFileDialog->metaObject()->invokeMethod(qtFileDialog, "accept");
     else
         qtFileDialog->metaObject()->invokeMethod(qtFileDialog, "reject");
 }
 
-QDialog::DialogCode QCocoaFileDialogHelper::dialogResultCode_sys()
+QPlatformDialogHelper::DialogCode QCocoaFileDialogHelper::dialogResultCode_sys()
 {
     QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *delegate = static_cast<QT_MANGLE_NAMESPACE(QNSOpenSavePanelDelegate) *>(mDelegate);
     return [delegate dialogResultCode];
diff --git a/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp b/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
index ce8fa08cb3..82fbd8c712 100644
--- a/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
+++ b/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
@@ -58,6 +58,7 @@
 #include <QtCore/QTimer>
 #include <QtCore/QDir>
 #include <QtCore/QScopedArrayPointer>
+#include <QtCore/QSharedPointer>
 #include <QtCore/QObject>
 #include <QtCore/QThread>
 #include <QtCore/private/qsystemlibrary_p.h>
@@ -353,17 +354,6 @@ Type dialogType(const QDialog *dialog)
 
 } // namespace QWindowsDialogs
 
-// Find the owner which to use as a parent of a native dialog.
-static inline HWND ownerWindow(const QDialog *dialog)
-{
-    if (QWidget *parent = dialog->nativeParentWidget())
-        if (QWindow *windowHandle = parent->windowHandle())
-            return QWindowsWindow::handleOf(windowHandle);
-    if (QWindow *fw = QGuiApplication::focusWindow())
-        return QWindowsWindow::handleOf(fw);
-    return 0;
-}
-
 /*!
     \class QWindowsNativeDialogBase
     \brief Base class for Windows native dialogs.
@@ -395,7 +385,7 @@ class QWindowsNativeDialogBase : public QObject
 public:
     virtual void setWindowTitle(const QString &title) = 0;
     virtual void exec(HWND owner = 0) = 0;
-    virtual QDialog::DialogCode result() const = 0;
+    virtual QPlatformDialogHelper::DialogCode result() const = 0;
 
 signals:
     void accepted();
@@ -425,13 +415,16 @@ protected:
     \ingroup qt-lighthouse-win
 */
 
-QWindowsDialogHelperBase::QWindowsDialogHelperBase(QDialog *dialog) :
+template <class BaseClass>
+QWindowsDialogHelperBase<BaseClass>::QWindowsDialogHelperBase(QDialog *dialog) :
     m_dialog(dialog),
-    m_nativeDialog(0)
+    m_nativeDialog(0),
+    m_ownerWindow(0)
 {
 }
 
-QWindowsNativeDialogBase *QWindowsDialogHelperBase::nativeDialog() const
+template <class BaseClass>
+QWindowsNativeDialogBase *QWindowsDialogHelperBase<BaseClass>::nativeDialog() const
 {
     if (!m_nativeDialog) {
          qWarning("%s invoked with no native dialog present.", __FUNCTION__);
@@ -440,7 +433,8 @@ QWindowsNativeDialogBase *QWindowsDialogHelperBase::nativeDialog() const
     return m_nativeDialog;
 }
 
-QWindowsNativeDialogBase *QWindowsDialogHelperBase::ensureNativeDialog()
+template <class BaseClass>
+QWindowsNativeDialogBase *QWindowsDialogHelperBase<BaseClass>::ensureNativeDialog()
 {
     // Create dialog and apply common settings.
     if (!m_nativeDialog) {
@@ -451,7 +445,8 @@ QWindowsNativeDialogBase *QWindowsDialogHelperBase::ensureNativeDialog()
     return m_nativeDialog;
 }
 
-void QWindowsDialogHelperBase::deleteNativeDialog_sys()
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::deleteNativeDialog_sys()
 {
     if (QWindowsContext::verboseDialogs)
         qDebug("%s" , __FUNCTION__);
@@ -491,29 +486,39 @@ void QWindowsDialogThread::run()
         qDebug("<%s" , __FUNCTION__);
 }
 
-bool QWindowsDialogHelperBase::setVisible_sys(bool visible)
+template <class BaseClass>
+bool QWindowsDialogHelperBase<BaseClass>::show_sys(QWindow *parent)
 {
-    const bool nonNative = nonNativeDialog();
     const bool modal = m_dialog->isModal();
+    if (parent) {
+        m_ownerWindow = QWindowsWindow::handleOf(parent);
+    } else {
+        m_ownerWindow = 0;
+    }
     if (QWindowsContext::verboseDialogs)
-        qDebug("%s visible=%d, native=%d, modal=%d native=%p" ,
-               __FUNCTION__, visible, !nonNative, modal, m_nativeDialog);
-    if (nonNative || (!visible && !m_nativeDialog) || (!modal && !supportsNonModalDialog()))
+        qDebug("%s modal=%d native=%p parent=%p" ,
+               __FUNCTION__, modal, m_nativeDialog, m_ownerWindow);
+    if (!modal && !supportsNonModalDialog())
         return false; // Was it changed in-between?
     if (!ensureNativeDialog())
         return false;
-    if (visible) {
-        if (!modal) { // Modal dialogs are shown in separate slot.
-            QWindowsDialogThread *thread = new QWindowsDialogThread(m_nativeDialog, ownerWindow(m_dialog));
-            thread->start();
-        }
-    } else {
-        m_nativeDialog->close();
+    if (!modal) { // Modal dialogs are shown in separate slot.
+        QWindowsDialogThread *thread = new QWindowsDialogThread(m_nativeDialog, m_ownerWindow);
+        thread->start();
     }
     return true;
 }
 
-void QWindowsDialogHelperBase::platformNativeDialogModalHelp()
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::hide_sys()
+{
+    if (m_nativeDialog)
+        m_nativeDialog->close();
+    m_ownerWindow = 0;
+}
+
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::platformNativeDialogModalHelp()
 {
     if (QWindowsContext::verboseDialogs)
         qDebug("%s" , __FUNCTION__);
@@ -522,17 +527,37 @@ void QWindowsDialogHelperBase::platformNativeDialogModalHelp()
                                        Qt::QueuedConnection);
 }
 
-void QWindowsDialogHelperBase::_q_platformRunNativeAppModalPanel()
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::_q_platformRunNativeAppModalPanel()
 {
     if (QWindowsNativeDialogBase *nd =nativeDialog())
-        nd->exec(ownerWindow(m_dialog));
+        nd->exec(m_ownerWindow);
 }
 
-QDialog::DialogCode QWindowsDialogHelperBase::dialogResultCode_sys()
+template <class BaseClass>
+QPlatformDialogHelper::DialogCode QWindowsDialogHelperBase<BaseClass>::dialogResultCode_sys()
 {
     if (QWindowsNativeDialogBase *nd =nativeDialog())
         return nd->result();
-    return QDialog::Rejected;
+    return QPlatformDialogHelper::Rejected;
+}
+
+static inline bool snapToDefaultButtonHint()
+{
+    BOOL snapToDefault = false;
+    if (SystemParametersInfo(SPI_GETSNAPTODEFBUTTON, 0, &snapToDefault, 0))
+        return snapToDefault;
+    return false;
+}
+
+template <class BaseClass>
+QVariant QWindowsDialogHelperBase<BaseClass>::styleHint(QPlatformDialogHelper::StyleHint hint) const
+{
+    switch (hint) {
+    case QPlatformDialogHelper::SnapToDefaultButton:
+        return QVariant(snapToDefaultButtonHint());
+    }
+    return BaseClass::styleHint(hint);
 }
 
 /*!
@@ -638,9 +663,9 @@ public:
     bool hideFiltersDetails() const    { return m_hideFiltersDetails; }
     void setHideFiltersDetails(bool h) { m_hideFiltersDetails = h; }
 
-    virtual QDialog::DialogCode result() const
+    virtual QPlatformDialogHelper::DialogCode result() const
         { return fileResult(); }
-    virtual QDialog::DialogCode fileResult(QStringList *fileResult = 0) const = 0;
+    virtual QPlatformDialogHelper::DialogCode fileResult(QStringList *fileResult = 0) const = 0;
     virtual QStringList selectedFiles() const = 0;
 
     inline void onFolderChange(IShellItem *);
@@ -953,21 +978,21 @@ HRESULT QWindowsNativeFileDialogEventHandler::OnTypeChange(IFileDialog *)
 class QWindowsNativeSaveFileDialog : public QWindowsNativeFileDialogBase
 {
 public:
-    virtual QDialog::DialogCode fileResult(QStringList *fileResult = 0) const;
+    virtual QPlatformDialogHelper::DialogCode fileResult(QStringList *fileResult = 0) const;
     virtual QStringList selectedFiles() const;
 };
 
-QDialog::DialogCode QWindowsNativeSaveFileDialog::fileResult(QStringList *result /* = 0 */) const
+QPlatformDialogHelper::DialogCode QWindowsNativeSaveFileDialog::fileResult(QStringList *result /* = 0 */) const
 {
     if (result)
         result->clear();
     IShellItem *item = 0;
     const HRESULT hr = fileDialog()->GetResult(&item);
     if (FAILED(hr) || !item)
-        return QDialog::Rejected;
+        return QPlatformDialogHelper::Rejected;
     if (result)
         result->push_back(QWindowsNativeFileDialogBase::itemPath(item));
-    return QDialog::Accepted;
+    return QPlatformDialogHelper::Accepted;
 }
 
 QStringList QWindowsNativeSaveFileDialog::selectedFiles() const
@@ -992,7 +1017,7 @@ QStringList QWindowsNativeSaveFileDialog::selectedFiles() const
 class QWindowsNativeOpenFileDialog : public QWindowsNativeFileDialogBase
 {
 public:
-    virtual QDialog::DialogCode fileResult(QStringList *fileResult = 0) const;
+    virtual QPlatformDialogHelper::DialogCode fileResult(QStringList *fileResult = 0) const;
     virtual QStringList selectedFiles() const;
 
 private:
@@ -1000,15 +1025,15 @@ private:
         { return static_cast<IFileOpenDialog *>(fileDialog()); }
 };
 
-QDialog::DialogCode QWindowsNativeOpenFileDialog::fileResult(QStringList *result /* = 0 */) const
+QPlatformDialogHelper::DialogCode QWindowsNativeOpenFileDialog::fileResult(QStringList *result /* = 0 */) const
 {
     if (result)
         result->clear();
     IShellItemArray *items = 0;
     const HRESULT hr = openFileDialog()->GetResults(&items);
     if (SUCCEEDED(hr) && items && QWindowsNativeFileDialogBase::itemPaths(items, result) > 0)
-        return QDialog::Accepted;
-    return QDialog::Rejected;
+        return QPlatformDialogHelper::Accepted;
+    return QPlatformDialogHelper::Rejected;
 }
 
 QStringList QWindowsNativeOpenFileDialog::selectedFiles() const
@@ -1053,7 +1078,7 @@ QWindowsNativeFileDialogBase *QWindowsNativeFileDialogBase::create(QFileDialog::
     \ingroup qt-lighthouse-win
 */
 
-class QWindowsFileDialogHelper : public QWindowsDialogHelperBase
+class QWindowsFileDialogHelper : public QWindowsDialogHelperBase<QPlatformFileDialogHelper>
 {
 public:
     explicit QWindowsFileDialogHelper(QDialog *dialog) :
@@ -1061,9 +1086,6 @@ public:
         m_fileDialog(qobject_cast<QFileDialog *>(dialog))
         { Q_ASSERT(m_fileDialog); }
 
-    virtual bool nonNativeDialog() const
-        { return m_fileDialog->testOption(QFileDialog::DontUseNativeDialog); }
-
     virtual bool defaultNameFilterDisables() const
         { return true; }
     virtual void setDirectory_sys(const QString &directory);
@@ -1093,13 +1115,13 @@ QWindowsNativeDialogBase *QWindowsFileDialogHelper::createNativeDialog()
     QObject::connect(result, SIGNAL(rejected()), m_fileDialog, SLOT(reject()),
                      Qt::QueuedConnection);
     QObject::connect(result, SIGNAL(directoryEntered(QString)),
-                     m_fileDialog, SIGNAL(directoryEntered(QString)),
+                     this, SIGNAL(directoryEntered(QString)),
                      Qt::QueuedConnection);
     QObject::connect(result, SIGNAL(currentChanged(QString)),
-                     m_fileDialog, SIGNAL(currentChanged(QString)),
+                     this, SIGNAL(currentChanged(QString)),
                      Qt::QueuedConnection);
     QObject::connect(result, SIGNAL(filterSelected(QString)),
-                     m_fileDialog, SIGNAL(filterSelected(QString)),
+                     this, SIGNAL(filterSelected(QString)),
                      Qt::QueuedConnection);
 
     // Apply settings.
@@ -1190,27 +1212,29 @@ QString QWindowsFileDialogHelper::selectedNameFilter_sys() const
     \ingroup qt-lighthouse-win
 */
 
+typedef QSharedPointer<QColor> SharedPointerColor;
+
 class QWindowsNativeColorDialog : public QWindowsNativeDialogBase
 {
     Q_OBJECT
 public:
-    explicit QWindowsNativeColorDialog(QColorDialog *dialog);
+    explicit QWindowsNativeColorDialog(const SharedPointerColor &color);
 
     virtual void setWindowTitle(const QString &) {}
     virtual void exec(HWND owner = 0);
-    virtual QDialog::DialogCode result() const { return m_code; }
+    virtual QPlatformDialogHelper::DialogCode result() const { return m_code; }
 
 public slots:
     virtual void close() {}
 
 private:
     COLORREF m_customColors[16];
-    QDialog::DialogCode m_code;
-    QColorDialog *m_dialog;
+    QPlatformDialogHelper::DialogCode m_code;
+    SharedPointerColor m_color;
 };
 
-QWindowsNativeColorDialog::QWindowsNativeColorDialog(QColorDialog *dialog) :
-    m_code(QDialog::Rejected), m_dialog(dialog)
+QWindowsNativeColorDialog::QWindowsNativeColorDialog(const SharedPointerColor &color) :
+    m_code(QPlatformDialogHelper::Rejected), m_color(color)
 {
     qFill(m_customColors, m_customColors + 16, COLORREF(0));
 }
@@ -1232,7 +1256,7 @@ void QWindowsNativeColorDialog::exec(HWND owner)
     chooseColor.lStructSize = sizeof(chooseColor);
     chooseColor.hwndOwner = owner;
     chooseColor.lpCustColors = m_customColors;
-    chooseColor.rgbResult = qColorToCOLORREF(m_dialog->currentColor());
+    chooseColor.rgbResult = qColorToCOLORREF(*m_color);
     chooseColor.Flags = CC_FULLOPEN | CC_RGBINIT;
     static ChooseColorWType chooseColorW = 0;
     if (!chooseColorW) {
@@ -1240,16 +1264,17 @@ void QWindowsNativeColorDialog::exec(HWND owner)
         chooseColorW = (ChooseColorWType)library.resolve("ChooseColorW");
     }
     if (chooseColorW) {
-        m_code = chooseColorW(&chooseColor) ? QDialog::Accepted :QDialog::Rejected;
+        m_code = chooseColorW(&chooseColor) ?
+            QPlatformDialogHelper::Accepted : QPlatformDialogHelper::Rejected;
         QWindowsDialogs::eatMouseMove();
     } else {
-        m_code = QDialog::Rejected;
+        m_code = QPlatformDialogHelper::Rejected;
     }
-    if (m_code == QDialog::Accepted) {
-        m_dialog->setCurrentColor(COLORREFToQColor(chooseColor.rgbResult));
+    if (m_code == QPlatformDialogHelper::Accepted) {
+        *m_color = COLORREFToQColor(chooseColor.rgbResult);
         emit accepted();
         if (QWindowsContext::verboseDialogs)
-            qDebug() << '<' << __FUNCTION__ << m_dialog->currentColor();
+            qDebug() << '<' << __FUNCTION__ << m_color;
     } else {
         emit rejected();
     }
@@ -1267,41 +1292,30 @@ void QWindowsNativeColorDialog::exec(HWND owner)
     \ingroup qt-lighthouse-win
 */
 
-class QWindowsColorDialogHelper : public QWindowsDialogHelperBase
+class QWindowsColorDialogHelper : public QWindowsDialogHelperBase<QPlatformColorDialogHelper>
 {
 public:
-    explicit QWindowsColorDialogHelper(QDialog *dialog) :
-        QWindowsDialogHelperBase(dialog),
-        m_colorDialog(qobject_cast<QColorDialog *>(dialog))
-        { Q_ASSERT(m_colorDialog); }
+    QWindowsColorDialogHelper(QDialog *dialog) :
+        QWindowsDialogHelperBase(dialog), m_currentColor(new QColor) { }
 
-    virtual bool nonNativeDialog() const
-        { return m_colorDialog->testOption(QColorDialog::DontUseNativeDialog); }
     virtual bool supportsNonModalDialog()
         { return false; }
 
-    // ### fixme: Remove once a dialog helper hierarchy is in place
-    virtual bool defaultNameFilterDisables() const { return true; }
-    virtual void setDirectory_sys(const QString &) {}
-    virtual QString directory_sys() const { return QString(); }
-    virtual void selectFile_sys(const QString &) {}
-    virtual QStringList selectedFiles_sys() const { return QStringList(); }
-    virtual void setFilter_sys() {}
-    virtual void setNameFilters_sys(const QStringList &) {}
-    virtual void selectNameFilter_sys(const QString &) {}
-    virtual QString selectedNameFilter_sys() const { return QString(); }
+    virtual QColor currentColor_sys() const { return *m_currentColor; }
+    virtual void setCurrentColor_sys(const QColor &c) { *m_currentColor = c; }
 
 private:
     inline QWindowsNativeColorDialog *nativeFileDialog() const
         { return static_cast<QWindowsNativeColorDialog *>(nativeDialog()); }
     virtual QWindowsNativeDialogBase *createNativeDialog()
-        { return new QWindowsNativeColorDialog(m_colorDialog); }
-    QColorDialog *m_colorDialog;
+        { return new QWindowsNativeColorDialog(m_currentColor); }
+    SharedPointerColor m_currentColor;
 };
 
-// QWindowsDialogHelperBase creation functions
+namespace QWindowsDialogs {
 
-bool QWindowsDialogHelperBase::useHelper(const QDialog *dialog)
+// QWindowsDialogHelperBase creation functions
+bool useHelper(const QDialog *dialog)
 {
     switch (QWindowsDialogs::dialogType(dialog)) {
     case QWindowsDialogs::FileDialog:
@@ -1317,7 +1331,7 @@ bool QWindowsDialogHelperBase::useHelper(const QDialog *dialog)
     return false;
 }
 
-QPlatformDialogHelper *QWindowsDialogHelperBase::create(QDialog *dialog)
+QPlatformDialogHelper *createHelper(QDialog *dialog)
 {
     if (QWindowsContext::verboseDialogs)
         qDebug("%s %p %s" , __FUNCTION__, dialog, dialog->metaObject()->className());
@@ -1336,6 +1350,7 @@ QPlatformDialogHelper *QWindowsDialogHelperBase::create(QDialog *dialog)
     return 0;
 }
 
+} // namespace QWindowsDialogs
 QT_END_NAMESPACE
 
 #include "qwindowsdialoghelpers.moc"
diff --git a/src/plugins/platforms/windows/qwindowsdialoghelpers.h b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
index 8566f00d55..99f3c0b2d2 100644
--- a/src/plugins/platforms/windows/qwindowsdialoghelpers.h
+++ b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
@@ -44,12 +44,14 @@
 
 #ifdef QT_WIDGETS_LIB
 
+#include "qtwindows_additional.h"
 #include <QtWidgets/qplatformdialoghelper_qpa.h>
 #include <QtCore/QStringList>
 
 QT_BEGIN_NAMESPACE
 
 class QFileDialog;
+class QDialog;
 class QWindowsNativeDialogBase;
 
 namespace QWindowsDialogs
@@ -58,21 +60,25 @@ namespace QWindowsDialogs
 
     Type dialogType(const QDialog *dialog);
     void eatMouseMove();
+
+    bool useHelper(const QDialog *dialog);
+    QPlatformDialogHelper *createHelper(QDialog *dialog);
 } // namespace QWindowsDialogs
 
-class QWindowsDialogHelperBase : public QPlatformDialogHelper
+template <class BaseClass>
+class QWindowsDialogHelperBase : public BaseClass
 {
 public:
-    static bool useHelper(const QDialog *dialog);
-    static QPlatformDialogHelper *create(QDialog *dialog);
 
     virtual void platformNativeDialogModalHelp();
     virtual void _q_platformRunNativeAppModalPanel();
     virtual void deleteNativeDialog_sys();
-    virtual bool setVisible_sys(bool visible);
-    virtual QDialog::DialogCode dialogResultCode_sys();
+    virtual bool show_sys(QWindow *parent);
+    virtual void hide_sys();
+    virtual QVariant styleHint(QPlatformDialogHelper::StyleHint) const;
+
+    virtual QPlatformDialogHelper::DialogCode dialogResultCode_sys();
 
-    virtual bool nonNativeDialog() const = 0;
     virtual bool supportsNonModalDialog() const { return true; }
 
 protected:
@@ -85,6 +91,7 @@ private:
 
     QDialog *m_dialog;
     QWindowsNativeDialogBase *m_nativeDialog;
+    HWND m_ownerWindow;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/windows/qwindowsintegration.cpp b/src/plugins/platforms/windows/qwindowsintegration.cpp
index 4975347748..4ffbdb7491 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.cpp
+++ b/src/plugins/platforms/windows/qwindowsintegration.cpp
@@ -325,12 +325,12 @@ QAbstractEventDispatcher * QWindowsIntegration::guiThreadEventDispatcher() const
 #ifdef QT_WIDGETS_LIB
 bool QWindowsIntegration::usePlatformNativeDialog(QDialog *dialog) const
 {
-    return QWindowsDialogHelperBase::useHelper(dialog);
+    return QWindowsDialogs::useHelper(dialog);
 }
 
 QPlatformDialogHelper *QWindowsIntegration::createPlatformDialogHelper(QDialog *dialog) const
 {
-    return QWindowsDialogHelperBase::create(dialog);
+    return QWindowsDialogs::createHelper(dialog);
 }
 
 #endif // QT_WIDGETS_LIB
diff --git a/src/widgets/dialogs/qcolordialog.cpp b/src/widgets/dialogs/qcolordialog.cpp
index 6b956b1277..1eaaf79bf5 100644
--- a/src/widgets/dialogs/qcolordialog.cpp
+++ b/src/widgets/dialogs/qcolordialog.cpp
@@ -1282,6 +1282,8 @@ inline bool QColorDialogPrivate::isAlphaVisible() const { return cs->isAlphaVisi
 
 QColor QColorDialogPrivate::currentQColor() const
 {
+    if (nativeDialogInUse)
+        return platformColorDialogHelper()->currentColor_sys();
     return cs->currentQColor();
 }
 
@@ -1650,6 +1652,13 @@ void QColorDialogPrivate::init(const QColor &initial)
     q->setCurrentColor(initial);
 }
 
+void QColorDialogPrivate::initHelper(QPlatformDialogHelper *h)
+{
+    QColorDialog *d = q_func();
+    QObject::connect(h, SIGNAL(currentColorChanged(QColor)), d, SIGNAL(currentColorChanged(QColor)));
+    QObject::connect(h, SIGNAL(colorSelected(QColor)), d, SIGNAL(colorSelected(QColor)));
+}
+
 void QColorDialogPrivate::_q_addCustom()
 {
     cusrgb[nextCust] = cs->currentColor();
@@ -1758,8 +1767,8 @@ void QColorDialog::setCurrentColor(const QColor &color)
     d->setCocoaPanelColor(color);
 #endif
     // ### fixme: Call helper
-    // if (d->nativeDialogInUse)
-    //    qt_guiPlatformPlugin()->colorDialogSetCurrentColor(this, color);
+    if (d->nativeDialogInUse)
+        d->platformColorDialogHelper()->setCurrentColor_sys(color);
 }
 
 QColor QColorDialog::currentColor() const
@@ -1768,7 +1777,6 @@ QColor QColorDialog::currentColor() const
     return d->currentQColor();
 }
 
-
 /*!
     Returns the color that the user selected by clicking the \gui{OK}
     or equivalent button.
@@ -1915,8 +1923,7 @@ void QColorDialog::setVisible(bool visible)
 #else
 
     if (!(d->opts & DontUseNativeDialog))
-        if (QPlatformDialogHelper *helper = d->platformHelper())
-            d->nativeDialogInUse = helper->setVisible_sys(visible);
+        d->setNativeDialogVisible(visible);
 
     if (d->nativeDialogInUse) {
         // Set WA_DontShowOnScreen so that QDialog::setVisible(visible) below
diff --git a/src/widgets/dialogs/qcolordialog_p.h b/src/widgets/dialogs/qcolordialog_p.h
index b2413f1418..39d7192b1d 100644
--- a/src/widgets/dialogs/qcolordialog_p.h
+++ b/src/widgets/dialogs/qcolordialog_p.h
@@ -75,6 +75,9 @@ class QColorDialogPrivate : public QDialogPrivate
     Q_DECLARE_PUBLIC(QColorDialog)
 
 public:
+    QPlatformColorDialogHelper *platformColorDialogHelper() const
+        { return static_cast<QPlatformColorDialogHelper *>(platformHelper()); }
+
     void init(const QColor &initial);
     QRgb currentColor() const;
     QColor currentQColor() const;
@@ -133,6 +136,8 @@ public:
     void _q_macRunNativeAppModalPanel();
     void mac_nativeDialogModalHelp();
 #endif
+private:
+    virtual void initHelper(QPlatformDialogHelper *h);
 };
 
 #endif // QT_NO_COLORDIALOG
diff --git a/src/widgets/dialogs/qdialog.cpp b/src/widgets/dialogs/qdialog.cpp
index 09c0127852..a0b0cdc564 100644
--- a/src/widgets/dialogs/qdialog.cpp
+++ b/src/widgets/dialogs/qdialog.cpp
@@ -64,16 +64,42 @@ QPlatformDialogHelper *QDialogPrivate::platformHelper() const
     // Delayed creation of the platform, ensuring that
     // that qobject_cast<> on the dialog works in the plugin.
     if (!m_platformHelperCreated) {
+        QDialogPrivate *ncThis = const_cast<QDialogPrivate *>(this);
         m_platformHelperCreated = true;
-        QDialog *dialog = const_cast<QDialog *>(q_func());
         m_platformHelper = QGuiApplicationPrivate::platformIntegration()
-                               ->createPlatformDialogHelper(dialog);
+                               ->createPlatformDialogHelper(ncThis->q_func());
         if (m_platformHelper)
-            m_platformHelper->d_ptr = const_cast<QDialogPrivate *>(this);
+            ncThis->initHelper(m_platformHelper);
     }
     return m_platformHelper;
 }
 
+QWindow *QDialogPrivate::parentWindow() const
+{
+    if (const QWidget *parent = q_func()->nativeParentWidget())
+        return parent->windowHandle();
+    return 0;
+}
+
+bool QDialogPrivate::setNativeDialogVisible(bool visible)
+{
+    if (QPlatformDialogHelper *helper = platformHelper()) {
+        if (visible) {
+            nativeDialogInUse = helper->show_sys(parentWindow());
+        } else {
+            helper->hide_sys();
+        }
+    }
+    return nativeDialogInUse;
+}
+
+QVariant QDialogPrivate::styleHint(QPlatformDialogHelper::StyleHint hint) const
+{
+    if (const QPlatformDialogHelper *helper = platformHelper())
+        return helper->styleHint(hint);
+    return QPlatformDialogHelper::defaultStyleHint(hint);
+}
+
 /*!
     \class QDialog
     \brief The QDialog class is the base class of dialog windows.
@@ -705,15 +731,9 @@ void QDialog::setVisible(bool visible)
         if (d->eventLoop)
             d->eventLoop->exit();
     }
-#ifdef Q_WS_WIN
-    if (d->mainDef && isActiveWindow()) {
-        BOOL snapToDefault = false;
-        if (SystemParametersInfo(SPI_GETSNAPTODEFBUTTON, 0, &snapToDefault, 0)) {
-            if (snapToDefault)
-                QCursor::setPos(d->mainDef->mapToGlobal(d->mainDef->rect().center()));
-        }
-    }
-#endif
+    if (d->mainDef && isActiveWindow()
+        && d->styleHint(QPlatformDialogHelper::SnapToDefaultButton).toBool())
+        QCursor::setPos(d->mainDef->mapToGlobal(d->mainDef->rect().center()));
 }
 
 /*!\reimp */
diff --git a/src/widgets/dialogs/qdialog_p.h b/src/widgets/dialogs/qdialog_p.h
index c88bda7b95..3d90686b6d 100644
--- a/src/widgets/dialogs/qdialog_p.h
+++ b/src/widgets/dialogs/qdialog_p.h
@@ -80,6 +80,10 @@ public:
         {}
     ~QDialogPrivate() { delete m_platformHelper; }
 
+    QWindow *parentWindow() const;
+    bool setNativeDialogVisible(bool visible);
+    QVariant styleHint(QPlatformDialogHelper::StyleHint hint) const;
+
     QPointer<QPushButton> mainDef;
     Qt::Orientation orientation;
     QWidget *extension;
@@ -110,6 +114,8 @@ public:
     QPlatformDialogHelper *platformHelper() const;
 
 private:
+    virtual void initHelper(QPlatformDialogHelper *) {}
+
     mutable QPlatformDialogHelper *m_platformHelper;
     mutable bool m_platformHelperCreated;
 };
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index 9b7c525c8b..75ba15af87 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -713,8 +713,7 @@ void QFileDialog::setVisible(bool visible)
         return;
 
     if (d->canBeNativeDialog()){
-        if (d->setVisible_sys(visible)){
-            d->nativeDialogInUse = true;
+        if (d->setNativeDialogVisible(visible)){
             // Set WA_DontShowOnScreen so that QDialog::setVisible(visible) below
             // updates the state correctly, but skips showing the non-native version:
             setAttribute(Qt::WA_DontShowOnScreen);
@@ -723,7 +722,6 @@ void QFileDialog::setVisible(bool visible)
             d->completer->setModel(0);
 #endif
         } else {
-            d->nativeDialogInUse = false;
             setAttribute(Qt::WA_DontShowOnScreen, false);
 #ifndef QT_NO_FSCOMPLETER
             if (d->proxyModel != 0)
@@ -2268,7 +2266,7 @@ void QFileDialogPrivate::createWidgets()
     Q_Q(QFileDialog);
     model = new QFileSystemModel(q);
     model->setObjectName(QLatin1String("qt_filesystem_model"));
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         model->setNameFilterDisables(helper->defaultNameFilterDisables());
     else
         model->setNameFilterDisables(false);
diff --git a/src/widgets/dialogs/qfiledialog_p.h b/src/widgets/dialogs/qfiledialog_p.h
index 6d4a00e681..383734950c 100644
--- a/src/widgets/dialogs/qfiledialog_p.h
+++ b/src/widgets/dialogs/qfiledialog_p.h
@@ -114,6 +114,9 @@ class Q_WIDGETS_EXPORT QFileDialogPrivate : public QDialogPrivate
 public:
     QFileDialogPrivate();
 
+    QPlatformFileDialogHelper *platformFileDialogHelper() const
+        { return static_cast<QPlatformFileDialogHelper *>(platformHelper()); }
+
     void createToolButtons();
     void createMenuActions();
     void createWidgets();
@@ -262,7 +265,6 @@ public:
     // dialog. Returning false means that a non-native dialog must be
     // used instead.
     bool canBeNativeDialog();
-    bool setVisible_sys(bool visible);
     void deleteNativeDialog_sys();
     QDialog::DialogCode dialogResultCode_sys();
 
@@ -289,6 +291,8 @@ public:
     ~QFileDialogPrivate();
 
 private:
+    virtual void initHelper(QPlatformDialogHelper *);
+
     Q_DISABLE_COPY(QFileDialogPrivate)
 };
 
@@ -344,6 +348,16 @@ private:
     QFileDialogPrivate *d_ptr;
 };
 
+void QFileDialogPrivate::initHelper(QPlatformDialogHelper *h)
+{
+    QFileDialog *d = q_func();
+    QObject::connect(h, SIGNAL(fileSelected(QString)), d, SIGNAL(fileSelected(QString)));
+    QObject::connect(h, SIGNAL(filesSelected(QStringList)), d, SIGNAL(filesSelected(QStringList)));
+    QObject::connect(h, SIGNAL(currentChanged(QString)), d, SIGNAL(currentChanged(QString)));
+    QObject::connect(h, SIGNAL(directoryEntered(QString)), d, SIGNAL(directoryEntered(QString)));
+    QObject::connect(h, SIGNAL(filterSelected(QString)), d, SIGNAL(filterSelected(QString)));
+}
+
 inline QModelIndex QFileDialogPrivate::mapToSource(const QModelIndex &index) const {
 #ifdef QT_NO_PROXYMODEL
     return index;
@@ -366,71 +380,68 @@ inline QString QFileDialogPrivate::rootPath() const {
 // Dummies for platforms that don't use native dialogs:
 inline void QFileDialogPrivate::deleteNativeDialog_sys()
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper()) {
         helper->deleteNativeDialog_sys();
-}
-
-inline bool QFileDialogPrivate::setVisible_sys(bool visible)
-{
-    if (QPlatformDialogHelper *helper = platformHelper())
-        return helper->setVisible_sys(visible);
-    return false;
+        nativeDialogInUse = false;
+    }
 }
 
 inline QDialog::DialogCode QFileDialogPrivate::dialogResultCode_sys()
 {
+    QDialog::DialogCode result = QDialog::Rejected;
     if (QPlatformDialogHelper *helper = platformHelper())
-        return helper->dialogResultCode_sys();
-    return QDialog::Rejected;
+        if (helper->dialogResultCode_sys() == QPlatformDialogHelper::Accepted)
+            result = QDialog::Accepted;
+    return result;
 }
 
 inline void QFileDialogPrivate::setDirectory_sys(const QString &directory)
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         helper->setDirectory_sys(directory);
 }
 
 inline QString QFileDialogPrivate::directory_sys() const
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         return helper->directory_sys();
     return QString();
 }
 
 inline void QFileDialogPrivate::selectFile_sys(const QString &filename)
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         helper->selectFile_sys(filename);
 }
 
 inline QStringList QFileDialogPrivate::selectedFiles_sys() const
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         return helper->selectedFiles_sys();
     return QStringList();
 }
 
 inline void QFileDialogPrivate::setFilter_sys()
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         helper->setFilter_sys();
 }
 
 inline void QFileDialogPrivate::setNameFilters_sys(const QStringList &filters)
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         helper->setNameFilters_sys(filters);
 }
 
 inline void QFileDialogPrivate::selectNameFilter_sys(const QString &filter)
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         helper->selectNameFilter_sys(filter);
 }
 
 inline QString QFileDialogPrivate::selectedNameFilter_sys() const
 {
-    if (QPlatformDialogHelper *helper = platformHelper())
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         return helper->selectedNameFilter_sys();
     return QString();
 }
diff --git a/src/widgets/dialogs/qfontdialog.cpp b/src/widgets/dialogs/qfontdialog.cpp
index 1b8a9137ac..1935a5aa73 100644
--- a/src/widgets/dialogs/qfontdialog.cpp
+++ b/src/widgets/dialogs/qfontdialog.cpp
@@ -490,6 +490,13 @@ bool QFontDialog::eventFilter(QObject *o , QEvent *e)
     return QDialog::eventFilter(o, e);
 }
 
+void QFontDialogPrivate::initHelper(QPlatformDialogHelper *h)
+{
+    QFontDialog *d = q_func();
+    QObject::connect(h, SIGNAL(currentFontChanged(QFont)), d, SIGNAL(currentFontChanged(QFont)));
+    QObject::connect(h, SIGNAL(fontSelected(QFont)), d, SIGNAL(fontSelected(QFont)));
+}
+
 /*
     Updates the contents of the "font family" list box. This
     function can be reimplemented if you have special requirements.
@@ -819,6 +826,8 @@ void QFontDialog::setCurrentFont(const QFont &font)
     d->strikeout->setChecked(font.strikeOut());
     d->underline->setChecked(font.underline());
     d->updateFamilies();
+    if (QPlatformFontDialogHelper *helper = d->platformFontDialogHelper())
+        helper->setCurrentFont_sys(font);
 
 #ifdef Q_WS_MAC
     if (d->delegate)
@@ -836,6 +845,8 @@ void QFontDialog::setCurrentFont(const QFont &font)
 QFont QFontDialog::currentFont() const
 {
     Q_D(const QFontDialog);
+    if (const QPlatformFontDialogHelper *helper = d->platformFontDialogHelper())
+        return helper->currentFont_sys();
     return d->sampleEdit->font();
 }
 
@@ -985,8 +996,7 @@ void QFontDialog::setVisible(bool visible)
         return;
     Q_D(QFontDialog);
     if (d->canBeNativeDialog())
-        if (QPlatformDialogHelper *helper = d->platformHelper())
-           d->nativeDialogInUse = helper->setVisible_sys(visible);
+        d->setNativeDialogVisible(visible);
     if (d->nativeDialogInUse) {
         // Set WA_DontShowOnScreen so that QDialog::setVisible(visible) below
         // updates the state correctly, but skips showing the non-native version:
diff --git a/src/widgets/dialogs/qfontdialog_p.h b/src/widgets/dialogs/qfontdialog_p.h
index 8b423f92d8..ef4e933624 100644
--- a/src/widgets/dialogs/qfontdialog_p.h
+++ b/src/widgets/dialogs/qfontdialog_p.h
@@ -57,6 +57,7 @@
 #include "private/qdialog_p.h"
 #include "qfontdatabase.h"
 #include "qfontdialog.h"
+#include "qplatformdialoghelper_qpa.h"
 
 #ifndef QT_NO_FONTDIALOG
 
@@ -80,6 +81,9 @@ public:
         : writingSystem(QFontDatabase::Any)
     { }
 
+    QPlatformFontDialogHelper *platformFontDialogHelper() const
+        { return static_cast<QPlatformFontDialogHelper *>(platformHelper()); }
+
     void updateFamilies();
     void updateStyles();
     void updateSizes();
@@ -156,6 +160,9 @@ public:
 
     static bool sharedFontPanelAvailable;
 #endif
+
+private:
+    virtual void initHelper(QPlatformDialogHelper *);
 };
 
 #endif // QT_NO_FONTDIALOG
diff --git a/src/widgets/kernel/qplatformdialoghelper_qpa.cpp b/src/widgets/kernel/qplatformdialoghelper_qpa.cpp
index 4ad3118053..daf864ff30 100644
--- a/src/widgets/kernel/qplatformdialoghelper_qpa.cpp
+++ b/src/widgets/kernel/qplatformdialoghelper_qpa.cpp
@@ -41,11 +41,50 @@
 
 #include "qplatformdialoghelper_qpa.h"
 
-QPlatformDialogHelper::QPlatformDialogHelper() :
-    d_ptr(0)
+#include <QtCore/QVariant>
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \class QPlatformDialogHelper
+    \since 5.0
+    \internal
+    \brief The QPlatformDialogHelper class allows for platform-specific customization of dialogs.
+
+*/
+
+/*!
+    \enum QPlatformDialogHelper::StyleHint
+
+    This enum type specifies platform-specific style hints.
+
+    \value SnapToDefaultButton Snap the mouse to the center of the default
+                               button. There is corresponding system
+                               setting on Windows.
+
+    \sa styleHint()
+*/
+
+QPlatformDialogHelper::QPlatformDialogHelper()
 {
 }
 
 QPlatformDialogHelper::~QPlatformDialogHelper()
 {
 }
+
+QVariant QPlatformDialogHelper::styleHint(StyleHint hint) const
+{
+    return QPlatformDialogHelper::defaultStyleHint(hint);
+}
+
+QVariant  QPlatformDialogHelper::defaultStyleHint(QPlatformDialogHelper::StyleHint hint)
+{
+    switch (hint) {
+    case QPlatformDialogHelper::SnapToDefaultButton:
+        return QVariant(false);
+    }
+    return QVariant();
+}
+
+QT_END_NAMESPACE
diff --git a/src/widgets/kernel/qplatformdialoghelper_qpa.h b/src/widgets/kernel/qplatformdialoghelper_qpa.h
index 2a3fbaa87e..970de611bc 100644
--- a/src/widgets/kernel/qplatformdialoghelper_qpa.h
+++ b/src/widgets/kernel/qplatformdialoghelper_qpa.h
@@ -43,7 +43,7 @@
 #define QPLATFORMDIALOGHELPER_H
 
 #include <qglobal.h>
-#include <qdialog.h>
+#include <qobject.h>
 
 QT_BEGIN_HEADER
 
@@ -52,23 +52,66 @@ QT_BEGIN_NAMESPACE
 QT_MODULE(Gui)
 
 class QString;
-class QObjectPrivate;
+class QColor;
+class QFont;
+class QWindow;
+class QVariant;
 
-class Q_WIDGETS_EXPORT QPlatformDialogHelper
+class Q_WIDGETS_EXPORT QPlatformDialogHelper : public QObject
 {
+    Q_OBJECT
 public:
+    enum StyleHint {
+        SnapToDefaultButton
+    };
+    enum DialogCode { Rejected, Accepted };
+
     QPlatformDialogHelper();
     virtual ~QPlatformDialogHelper();
 
+    virtual QVariant styleHint(StyleHint hint) const;
+
     virtual void platformNativeDialogModalHelp() = 0;
     virtual void _q_platformRunNativeAppModalPanel() = 0;
 
-    virtual bool defaultNameFilterDisables() const = 0;
-
     virtual void deleteNativeDialog_sys() = 0;
-    virtual bool setVisible_sys(bool visible) = 0;
-    virtual QDialog::DialogCode dialogResultCode_sys() = 0;
+    virtual bool show_sys(QWindow *parent) = 0;
+    virtual void hide_sys() = 0;
+
+    virtual DialogCode dialogResultCode_sys() = 0;
+
+    static QVariant defaultStyleHint(QPlatformDialogHelper::StyleHint hint);
+};
+
+class Q_WIDGETS_EXPORT QPlatformColorDialogHelper : public QPlatformDialogHelper
+{
+    Q_OBJECT
+public:
+    virtual void setCurrentColor_sys(const QColor &) = 0;
+    virtual QColor currentColor_sys() const = 0;
 
+Q_SIGNALS:
+    void currentColorChanged(const QColor &color);
+    void colorSelected(const QColor &color);
+};
+
+class Q_WIDGETS_EXPORT QPlatformFontDialogHelper : public QPlatformDialogHelper
+{
+    Q_OBJECT
+public:
+    virtual void setCurrentFont_sys(const QFont &) = 0;
+    virtual QFont currentFont_sys() const = 0;
+
+Q_SIGNALS:
+    void currentFontChanged(const QFont &font);
+    void fontSelected(const QFont &font);
+};
+
+class Q_WIDGETS_EXPORT QPlatformFileDialogHelper : public QPlatformDialogHelper
+{
+    Q_OBJECT
+public:
+    virtual bool defaultNameFilterDisables() const = 0;
     virtual void setDirectory_sys(const QString &directory) = 0;
     virtual QString directory_sys() const = 0;
     virtual void selectFile_sys(const QString &filename) = 0;
@@ -78,7 +121,12 @@ public:
     virtual void selectNameFilter_sys(const QString &filter) = 0;
     virtual QString selectedNameFilter_sys() const = 0;
 
-    QObjectPrivate *d_ptr;
+Q_SIGNALS:
+    void fileSelected(const QString &file);
+    void filesSelected(const QStringList &files);
+    void currentChanged(const QString &path);
+    void directoryEntered(const QString &directory);
+    void filterSelected(const QString &filter);
 };
 
 QT_END_NAMESPACE