Also set mouse position in ITEM_BEGIN_DRAG event in wxDataViewCtrl under GTK+, part of #12582: enhancing wxDataViewCtrl

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65870 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dataview.cpp

@@ -3516,6 +3516,9 @@ gboolean wxDataViewCtrlInternal::row_draggable( GtkTreeDragSource *WXUNUSED(drag
     event.SetEventObject( m_owner );
     event.SetItem( item );
     event.SetModel( m_wx_model );
+    gint x, y;
+    gtk_widget_get_pointer(m_owner->GtkGetTreeView(), &x, &y);
+    event.SetPosition(x, y);
     if (!m_owner->HandleWindowEvent( event ))
         return FALSE;