Cocoa integration - implement Qt::WindowModal file dialogs

Previously, for Qt::WindowModal dialogs  we were creating modal sheet with beginSheetModalForWindow:
and later (from exec) calling -runModal, essentially making a window modal dialog into (now) application
modal sheet, which is not right- it's centered relative to desktop and the jump from window modal sheet's
position (centered relative to a window) to application modal was quite visible.
Now, instead of [panel runModal] (== [NSApp runModalForWindow:panel])
we call [NSApp runModalForWindow:theRequiredWindow].

Change-Id: I793dc72c7d1fe96497bb35754f4d0eac9a5e00e5
Reviewed-by: Morten Johan Sørvig <morten.sorvig@theqtcompany.com>

src/gui/kernel/qplatformdialoghelper.cpp

@@ -137,6 +137,12 @@ QVariant  QPlatformDialogHelper::defaultStyleHint(QPlatformDialogHelper::StyleHi
     return QVariant();
 }
 
+void QPlatformDialogHelper::execModalForWindow(QWindow *parent)
+{
+    Q_UNUSED(parent);
+    exec();
+}
+
 // Font dialog
 
 class QFontDialogOptionsPrivate : public QSharedData

src/gui/kernel/qplatformdialoghelper.h

@@ -145,6 +145,7 @@ public:
     virtual QVariant styleHint(StyleHint hint) const;
 
     virtual void exec() = 0;
+    virtual void execModalForWindow(QWindow *parent);
     virtual bool show(Qt::WindowFlags windowFlags,
                           Qt::WindowModality windowModality,
                           QWindow *parent) = 0;

src/plugins/platforms/cocoa/qcocoafiledialoghelper.h

@@ -51,6 +51,7 @@ public:
     virtual ~QCocoaFileDialogHelper();
 
     void exec();
+    void execModalForWindow(QWindow *parent);
 
     bool defaultNameFilterDisables() const;
 

src/plugins/platforms/cocoa/qcocoafiledialoghelper.mm

@@ -254,17 +254,22 @@ static QString strippedText(QString s)
         || [self panel:nil shouldShowFilename:filepath];
 
     [self updateProperties];
-    QCocoaMenuBar::redirectKnownMenuItemsToFirstResponder();
     [mSavePanel setDirectoryURL: [NSURL fileURLWithPath:mCurrentDir]];
 
     [mSavePanel setNameFieldStringValue:selectable ? QCFString::toNSString(info.fileName()) : @""];
     NSWindow *nsparent = static_cast<NSWindow *>(qGuiApp->platformNativeInterface()->nativeResourceForWindow("nswindow", parent));
 
+    qApp->processEvents(QEventLoop::ExcludeUserInputEvents | QEventLoop::ExcludeSocketNotifiers);
+    QCocoaMenuBar::redirectKnownMenuItemsToFirstResponder();
+
     [mSavePanel beginSheetModalForWindow:nsparent completionHandler:^(NSInteger result){
-        mReturnCode = result;
+        [[NSApplication sharedApplication] stopModalWithCode:result];
-        if (mHelper)
-            mHelper->QNSOpenSavePanelDelegate_panelClosed(result == NSOKButton);
     }];
+
+    mReturnCode = [[NSApplication sharedApplication] runModalForWindow:nsparent];
+    QAbstractEventDispatcher::instance()->interrupt();
+    if (mHelper)
+        mHelper->QNSOpenSavePanelDelegate_panelClosed(mReturnCode == NSOKButton);
 }
 
 - (BOOL)isHiddenFile:(NSString *)filename isDir:(BOOL)isDir
@@ -706,14 +711,15 @@ void QCocoaFileDialogHelper::createNSOpenSavePanelDelegate()
 
 bool QCocoaFileDialogHelper::showCocoaFilePanel(Qt::WindowModality windowModality, QWindow *parent)
 {
+    Q_UNUSED(parent)
+
     createNSOpenSavePanelDelegate();
     if (!mDelegate)
         return false;
     if (windowModality == Qt::NonModal)
         [mDelegate showModelessPanel];
-    else if (windowModality == Qt::WindowModal && parent)
+    // no need to show a Qt::ApplicationModal dialog here, since it will be done in exec;
-        [mDelegate showWindowModalSheet:parent];
+    // Qt::WindowModal will be done in execModalForWindow.
-    // no need to show a Qt::ApplicationModal dialog here, since it will be done in _q_platformRunNativeAppModalPanel()
     return true;
 }
 
@@ -745,6 +751,14 @@ void QCocoaFileDialogHelper::exec()
 
 }
 
+void QCocoaFileDialogHelper::execModalForWindow(QWindow *parent)
+{
+    if (!parent)
+        return exec();
+
+    [mDelegate showWindowModalSheet:parent];
+}
+
 bool QCocoaFileDialogHelper::defaultNameFilterDisables() const
 {
     return true;

src/widgets/dialogs/qdialog.cpp

@@ -534,7 +534,10 @@ int QDialog::exec()
 
     QPointer<QDialog> guard = this;
     if (d->nativeDialogInUse) {
-        d->platformHelper()->exec();
+        if (windowModality() == Qt::WindowModal)
+            d->platformHelper()->execModalForWindow(d->parentWindow());
+        else
+            d->platformHelper()->exec();
     } else {
         QEventLoop eventLoop;
         d->eventLoop = &eventLoop;