Resolves: tdf#124980 drop dangling timer

Change-Id: I05ec394ee83f0422ecccf3ae3377818af6feb1d1
Reviewed-on: https://gerrit.libreoffice.org/71398
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

vcl/unx/gtk3/gtk3gtkinst.cxx

@@ -9041,6 +9041,8 @@ public:
 
     virtual ~GtkInstanceEntryTreeView() override
     {
+        if (m_nAutoCompleteIdleId)
+            g_source_remove(m_nAutoCompleteIdleId);
         GtkWidget* pWidget = m_pEntry->getWidget();
         g_signal_handler_disconnect(pWidget, m_nKeyPressSignalId);
         g_signal_handler_disconnect(pWidget, m_nEntryInsertTextSignalId);