Set event object for wxEVT_DATAVIEW_SELECTION_CHANGED events in wxGTK.

The event object was always NULL for these events before as we didn't set it
at all.

Closes #13478.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75138 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dataview.cpp

@@ -4260,6 +4260,7 @@ wxdataview_selection_changed_callback( GtkTreeSelection* WXUNUSED(selection), wx
         return;
 
     wxDataViewEvent event( wxEVT_DATAVIEW_SELECTION_CHANGED, dv->GetId() );
+    event.SetEventObject( dv );
     event.SetItem( dv->GetSelection() );
     event.SetModel( dv->GetModel() );
     dv->HandleWindowEvent( event );