Hi, after some more research, it turns out that the actual bug is in Tk. We'll try to locate the code in question and report it upstream, possibly even sending a patch along. Current ETA (subject to change): End of April, 2017 -Stefan -- BAUR-ITCS UG (haftungsbeschränkt) Geschäftsführer: Stefan Baur Eichenäckerweg 10, 89081 Ulm | Registergericht Ulm, HRB 724364 Fon/Fax 0731 40 34 66-36/-35 | USt-IdNr.: DE268653243