Reset active undo stask on editor close

Closes #951

changed milestone to %14 Fix issues reported in gitlab

added Bug Critical Doing QtC labels

requested review from @alejandro_exojo_viking

By Guenter Schwann on 2023-04-12T14:17:24

assigned to @alejandro_exojo_viking

By Guenter Schwann on 2023-04-12T14:17:24

approved this merge request

By Alejandro Exojo on 2023-04-12T15:26:25

merged