tdf#124027: use ID of the embedded window and fix position of overlay

1) after many trials and errors what LibO apparently expects here is
the ID of QWindow parent of [embedded] system child window

2) the position of the embedded window for video overlay has already
been translated relative to the top-left corner of the slide (see
bugfix of tdf#42873 how) in gen, gtk and kde5 vclplugs. So let's limit
translating it 2nd time only to gtk3 vclplug which for some reason
behaves differently 
(regression from 18138417485aeba6c52d935c616dba829b24ffd8)

Change-Id: Ie4c6d14a50959c0fdd04e745918d4889c9da45ec
Reviewed-on: https://gerrit.libreoffice.org/72458
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
diff --git a/avmedia/source/gstreamer/gstplayer.cxx b/avmedia/source/gstreamer/gstplayer.cxx
index 78928cd..6303bc5 100644
--- a/avmedia/source/gstreamer/gstplayer.cxx
+++ b/avmedia/source/gstreamer/gstplayer.cxx
@@ -926,19 +926,27 @@ uno::Reference< ::media::XPlayerWindow > SAL_CALL Player::createPlayerWindow( co
            rArguments[ 2 ] >>= pIntPtr;
            SystemChildWindow *pParentWindow = reinterpret_cast< SystemChildWindow* >( pIntPtr );

            if (pParentWindow)
            {
                Point aPoint = pParentWindow->GetPosPixel();
                maArea.X = aPoint.getX();
                maArea.Y = aPoint.getY();
            }

            const SystemEnvData* pEnvData = pParentWindow ? pParentWindow->GetSystemData() : nullptr;
            OSL_ASSERT(pEnvData);
            if (pEnvData)
            {
                OUString aToolkit = OUString::createFromAscii(pEnvData->pToolkit);

                // tdf#124027: the position of embedded window is identical w/ the position
                // of media object in all other vclplugs (gtk, kde5, gen), in gtk3 w/o gtksink it
                // needs to be translated
                if (aToolkit == "gtk3")
                {
                    if (pParentWindow)
                    {
                        Point aPoint = pParentWindow->GetPosPixel();
                        maArea.X = aPoint.getX();
                        maArea.Y = aPoint.getY();
                    }
                }

#if defined(ENABLE_GTKSINK)
                GstElement *pVideosink = g_strcmp0(pEnvData->pToolkit, "gtk3") == 0 ?
                GstElement *pVideosink = (aToolkit == "gtk3") ?
                                           gst_element_factory_make("gtksink", "gtksink") : nullptr;
                if (pVideosink)
                {
diff --git a/vcl/qt5/Qt5Object.cxx b/vcl/qt5/Qt5Object.cxx
index b195272..0f3a4f2 100644
--- a/vcl/qt5/Qt5Object.cxx
+++ b/vcl/qt5/Qt5Object.cxx
@@ -40,7 +40,7 @@ Qt5Object::Qt5Object(Qt5Frame* pParent, bool bShow)
        m_pQWidget->show();

    m_aSystemData.nSize = sizeof(SystemEnvData);
    m_aSystemData.aWindow = pParent->GetQWidget()->winId();
    m_aSystemData.aWindow = m_pQWindow->winId(); // ID of the embedded window
    m_aSystemData.aShellWindow = reinterpret_cast<sal_IntPtr>(this);
    //m_aSystemData.pSalFrame = this;
    //m_aSystemData.pWidget = m_pQWidget;