<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> Oh gosh, You are my hero Juan! I was focusing on the list model been garbage collected, but it was the issue of the visitor. It was a local variable in a preference browser method so I tuned it as an instance variable and voilà! Here is how looks like the Preference browser with the use of the widget and panel in cuis-smalltalk-UI: <img moz-do-not-send="false" src="cid:part1.OzepPOce.0XFVCkLZ@drgeo.eu" alt="" width="910" height="323"> Thanks <div class="moz-cite-prefix">Le 26/05/2022 à 04:39, Juan Vuletich a écrit : </div> <blockquote type="cite" cite="mid:628EE85A.9050104@zoho.com"> Have you taken into account that receiver and arguments of #when:send:to: and friends are only held weakly? This means that if there is no other (strong) reference to them, they can be garbage collected anytime and will become nil. This is not "corruption", but how #when:send:to: works. I believe (not absolutely sure) it is the same in other Smalltalk dialects. HTH, </blockquote> <pre class="moz-signature" cols="72">-- GNU Dr. Geo <a class="moz-txt-link-freetext" href="http://drgeo.eu">http://drgeo.eu</a> <a class="moz-txt-link-freetext" href="http://blog.drgeo.eu">http://blog.drgeo.eu</a></pre> </body> </html>