Resolves: tdf#100097 dbaccess self-dnd depends on getting its own transferable

on drop that it set on drag. It does some uno tunnel foo to drag the data it
needs back out of it in some grotesque fashion.

So we have to follow the same style of hackery as under MacOSX to detect
on drop that there is an active drag started by ourself and so use that
active drag's transferable as the source transferable for the drop, rather
that use the intermediate universal GtkDnDTransferable.

Change-Id: I3c3a94416db908603bde8f15dc5b1c9d726b8dbd
(cherry picked from commit 73f84ab139cb1d2564f9292fba08d69a0ab822c1)

4 files changed, 41 insertions, 9 deletions

diff --git a/vcl/inc/unx/gtk/gtkinst.hxx b/vcl/inc/unx/gtk/gtkinst.hxx
index 6f1f9999bc9b..5218eb4686f3 100644
--- a/vcl/inc/unx/gtk/gtkinst.hxx
+++ b/vcl/inc/unx/gtk/gtkinst.hxx
@@ -171,6 +171,11 @@ public:
     void dragDelete();
     void dragEnd(GdkDragContext* context);
     void dragDataGet(GtkSelectionData *data, guint info);
+
+    // For LibreOffice internal D&D we provide the Transferable without Gtk
+    // intermediaries as a shortcut, see tdf#100097 for how dbaccess depends on this
+    static GtkDragSource* g_ActiveDragSource;
+    css::uno::Reference<css::datatransfer::XTransferable> GetTransferrable() const { return m_xTrans; }
 };
 
 #endif
diff --git a/vcl/osx/DragSource.cxx b/vcl/osx/DragSource.cxx
index c72b4bcaa2d0..d794d1fb808d 100644
--- a/vcl/osx/DragSource.cxx
+++ b/vcl/osx/DragSource.cxx
@@ -47,8 +47,8 @@ using namespace com::sun::star::awt;
 using namespace com::sun::star::lang;
 using namespace comphelper;
 
-// For OOo internal D&D we provide the Transferable without NSDragPboard
-// interference as a shortcut
+// For LibreOffice internal D&D we provide the Transferable without NSDragPboard
+// interference as a shortcut, see tdf#100097 for how dbaccess depends on this
 uno::Reference<XTransferable> DragSource::g_XTransferable;
 NSView* DragSource::g_DragSourceView = nil;
 bool DragSource::g_DropSuccessSet = false;
diff --git a/vcl/unx/gtk3/gtk3gtkframe.cxx b/vcl/unx/gtk3/gtk3gtkframe.cxx
index 0bb9bf740416..2c0461657dc4 100644
--- a/vcl/unx/gtk3/gtk3gtkframe.cxx
+++ b/vcl/unx/gtk3/gtk3gtkframe.cxx
@@ -3296,6 +3296,10 @@ public:
     }
 };
 
+// For LibreOffice internal D&D we provide the Transferable without Gtk
+// intermediaries as a shortcut, see tdf#100097 for how dbaccess depends on this
+GtkDragSource* GtkDragSource::g_ActiveDragSource;
+
 gboolean GtkSalFrame::signalDragDrop(GtkWidget* pWidget, GdkDragContext* context, gint x, gint y, guint time, gpointer frame)
 {
     GtkSalFrame* pThis = static_cast<GtkSalFrame*>(frame);
@@ -3310,7 +3314,13 @@ gboolean GtkSalFrame::signalDragDrop(GtkWidget* pWidget, GdkDragContext* context
     aEvent.LocationY = y;
     aEvent.DropAction = GdkToVcl(gdk_drag_context_get_selected_action(context));
     aEvent.SourceActions = GdkToVcl(gdk_drag_context_get_actions(context));
-    css::uno::Reference<css::datatransfer::XTransferable> xTransferable(new GtkDnDTransferable(context, time, pWidget, pThis));
+    css::uno::Reference<css::datatransfer::XTransferable> xTransferable;
+    // For LibreOffice internal D&D we provide the Transferable without Gtk
+    // intermediaries as a shortcut, see tdf#100097 for how dbaccess depends on this
+    if (GtkDragSource::g_ActiveDragSource)
+        xTransferable = GtkDragSource::g_ActiveDragSource->GetTransferrable();
+    else
+        xTransferable = new GtkDnDTransferable(context, time, pWidget, pThis);
     aEvent.Transferable = xTransferable;
 
     pThis->m_pDropTarget->fire_drop(aEvent);
@@ -3366,7 +3376,7 @@ void GtkSalFrame::signalDragDropReceived(GtkWidget* /*pWidget*/, GdkDragContext
     pThis->m_pFormatConversionRequest->LoopEnd(gtk_selection_data_copy(data));
 }
 
-gboolean GtkSalFrame::signalDragMotion(GtkWidget *widget, GdkDragContext *context, gint x, gint y, guint time, gpointer frame)
+gboolean GtkSalFrame::signalDragMotion(GtkWidget *pWidget, GdkDragContext *context, gint x, gint y, guint time, gpointer frame)
 {
     GtkSalFrame* pThis = static_cast<GtkSalFrame*>(frame);
 
@@ -3374,7 +3384,7 @@ gboolean GtkSalFrame::signalDragMotion(GtkWidget *widget, GdkDragContext *contex
         return false;
 
     if (!pThis->m_bInDrag)
-        gtk_drag_highlight(widget);
+        gtk_drag_highlight(pWidget);
 
     css::datatransfer::dnd::DropTargetDragEnterEvent aEvent;
     aEvent.Source = static_cast<css::datatransfer::dnd::XDropTarget*>(pThis->m_pDropTarget);
@@ -3391,8 +3401,14 @@ gboolean GtkSalFrame::signalDragMotion(GtkWidget *widget, GdkDragContext *contex
 
     if (!pThis->m_bInDrag)
     {
-        css::uno::Reference<css::datatransfer::XTransferable> xTrans(new GtkDnDTransferable(context, time, widget, pThis));
-        css::uno::Sequence<css::datatransfer::DataFlavor> aFormats = xTrans->getTransferDataFlavors();
+        css::uno::Reference<css::datatransfer::XTransferable> xTransferable;
+        // For LibreOffice internal D&D we provide the Transferable without Gtk
+        // intermediaries as a shortcut, see tdf#100097 for how dbaccess depends on this
+        if (GtkDragSource::g_ActiveDragSource)
+            xTransferable = GtkDragSource::g_ActiveDragSource->GetTransferrable();
+        else
+            xTransferable = new GtkDnDTransferable(context, time, pWidget, pThis);
+        css::uno::Sequence<css::datatransfer::DataFlavor> aFormats = xTransferable->getTransferDataFlavors();
         aEvent.SupportedDataFlavors = aFormats;
         pThis->m_pDropTarget->fire_dragEnter(aEvent);
         pThis->m_bInDrag = true;
@@ -3405,13 +3421,13 @@ gboolean GtkSalFrame::signalDragMotion(GtkWidget *widget, GdkDragContext *contex
     return true;
 }
 
-void GtkSalFrame::signalDragLeave(GtkWidget *widget, GdkDragContext * /*context*/, guint /*time*/, gpointer frame)
+void GtkSalFrame::signalDragLeave(GtkWidget *pWidget, GdkDragContext * /*context*/, guint /*time*/, gpointer frame)
 {
     GtkSalFrame* pThis = static_cast<GtkSalFrame*>(frame);
     if (!pThis->m_pDropTarget)
         return;
     pThis->m_bInDrag = false;
-    gtk_drag_unhighlight(widget);
+    gtk_drag_unhighlight(pWidget);
 
 #if 0
     css::datatransfer::dnd::DropTargetEvent aEvent;
@@ -4059,6 +4075,10 @@ void GtkDragSource::startDrag(const datatransfer::dnd::DragGestureEvent& rEvent,
                 nDragButton = 2;
         }
 
+        // For LibreOffice internal D&D we provide the Transferable without Gtk
+        // intermediaries as a shortcut, see tdf#100097 for how dbaccess depends on this
+        g_ActiveDragSource = this;
+
         m_pFrame->startDrag(nDragButton, rEvent.DragOriginX, rEvent.DragOriginY,
                             VclToGdk(sourceActions), pTargetList);
         gtk_target_list_unref(pTargetList);
@@ -4145,6 +4165,7 @@ void GtkDragSource::dragEnd(GdkDragContext* context)
     aEv.DropAction = GdkToVcl(gdk_drag_context_get_selected_action(context));
     aEv.DropSuccess = gdk_drag_drop_succeeded(context);
     m_xListener->dragDropEnd(aEv);
+    g_ActiveDragSource = nullptr;
 }
 
 void GtkSalFrame::signalDragEnd(GtkWidget* /*widget*/, GdkDragContext* context, gpointer frame)
diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index 768f4b15e2ba..ed64ded2ece5 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -824,6 +824,12 @@ GtkDragSource::~GtkDragSource()
 {
     if (m_pFrame)
         m_pFrame->deregisterDragSource(this);
+
+    if (GtkDragSource::g_ActiveDragSource == this)
+    {
+        SAL_WARN( "vcl.gtk", "dragEnd should have been called on GtkDragSource before dtor");
+        GtkDragSource::g_ActiveDragSource = nullptr;
+    }
 }
 
 void GtkDragSource::deinitialize()